Defendant first assigns as error the denial of his motions to dismiss the charge of first-degree murder on the ground that there was insufficient evidence of premeditation and deliberation.
In order for the trial court to submit a charge of first degree murder to the jury, there must have been substantial evidence presented from which a jury could determine that the defendant intentionally shot and killed the victim with malice, premeditation and deliberation. State v. Horton, 299 N.C. 690, 263 S.E. 2d 745 (1980); State v. Heavener, 298 N.C. 541, 259 S.E. 2d 227 (1979); State v. Baggett, 293 N.C. 307, 237 S.E. 2d 827 (1977). “Substantial evidence” is that amount of *470relevant evidence that a reasonable mind might accept as sufficient to support a conclusion. State v. Smith, 300 N.C. 71, 265 S.E. 2d 164 (1980); State v. Powell, 299 N.C. 95, 261 S.E. 2d 114 (1980). In ruling upon defendant’s motion to dismiss on the grounds of insufficient evidence, the trial court is required to interpret the evidence in the light most favorable to the State, drawing all reasonable inferences in the State’s favor. State v. Fletcher, 301 N.C. 709, 272 S.E. 2d 859 (1981); State v. King, 299 N.C. 707, 264 S.E. 2d 40 (1980).
Premeditation has been defined by this Court as thought beforehand for some length of time, however short. No particular length of time is required; it is sufficient if the process of premeditation occurred at any point prior to the killing. State v. Myers, 299 N.C. 671, 263 S.E. 2d 768 (1980); State v. Reams, 277 N.C. 391, 178 S.E. 2d 65 (1970); State v. Robbins, 275 N.C. 537, 169 S.E. 2d 858 (1969). An unlawful killing is committed with deliberation if it is done in a “cool state of blood,” without legal provocation and in furtherance of a “fixed design to gratify a feeling of revenge, or to accomplish some unlawful purpose.” State v. Faust, 254 N.C. 101, 106-07, 118 S.E. 2d 769, 772 (1961). The intent to kill must arise from “a fixed determination previously formed after weighing the matter.” State v. Exum, 138 N.C. 599, 618, 50 S.E. 283, 289 (1905). See also State v. Baggett, supra; State v. Britt, 285 N.C. 256, 204 S.E. 2d 817 (1974).
[t]he term “cool state of blood” does not mean that the defendant must be calm or tranquil or display the absence of emotion; rather, the defendant’s anger or emotion must not have been such as to disturb the defendant’s faculties and reason. State v. Myers, 299 N.C. 671, 263 S.E. 2d 768 (1980); State v. Britt, 285 N.C. 256, 204 S.E. 2d 817 (1974). The fact that there was a quarrel does not preclude the possibility that the defendant formed the intent to kill with premeditation and deliberation. State v. Tysor, 307 N.C. 679, 300 S.E. 2d 366 (1983); State v. Misenheimer, 304 N.C. 108, 282 S.E. 2d 791 (1981).
In the instant case, the evidence, taken in the light most favorable to the State, tends to show that Officer Enevold *471stopped to investigate a suspicious vehicle, and as he looked into the window of the car, a black man appeared and took off running. The officer on two occasions said something, but the man kept on running. Officer Enevold ran after him and tackled him. As the two struggled, the man managed to get up. The officer was still on the ground. The black man, who had possession of the gun, was “looking down at his face and . . . said something like, ‘Let me go.’ ” A shot was fired and the officer fell to the ground. Immediately following the shooting, the man turned and pointed the gun at Ricky Edwards, an eyewitness who was seated in his automobile at the time. The man then fled the scene in the blue GTO, “going faster than the speed limit.” This evidence was sufficient to permit the issues of premeditation and deliberation to go to the jury.
 Defendant next assigns as error the failure of the trial court to instruct the jury on the lesser-included offense of involuntary manslaughter. At trial, defendant submitted a written request for a jury instruction on involuntary manslaughter. The trial court denied the request and charged the jury on the offenses of first-degree murder, second-degree murder, and voluntary manslaughter. In support of his contention, defendant argues that the evidence permits an inference that the officer’s gun went off accidentally as a result of defendant’s negligent handling of it. We disagree.
[ijnvoluntary manslaughter is the unintentional killing of a human being without malice, proximately caused by (1) an unlawful act not amounting to a felony nor naturally dangerous to human life, or (2) a culpably negligent act or omission. State v. Ward, 286 N.C. 304, 210 S.E. 2d 407.
Id. at 321, 230 S.E. 2d at 153. In the instant case, defendant did not testify or put on any evidence. The State’s evidence tends to show that in the course of a struggle in which defendant was trying to get away, defendant stood up and looked down at the officer. At that point defendant said “Let me go” and a gun in his possession went off. The gun was pointed at Officer Enevold and was fired at extremely close range. The officer fell to the ground and immediately thereafter defendant turned toward Ricky Edwards and pointed the gun at him. Defendant then fled the scene in the blue GTO. There is no evidence of an unintentional dis*472charge of the weapon and hence there was no error in the failure of the trial judge to instruct on involuntary manslaughter. See State v. Robbins, 309 N.C. 771, 309 S.E. 2d 188 (1983).
 Defendant next contends that he was denied his right to a fair trial by the prosecutor’s closing argument during the guilt phase of the trial. Defendant maintains that certain portions of the prosecutor’s closing argument improperly appealed to the passions and prejudices of the jurors. Although conceding he made no objections to the challenged portions, defendant argues that the remarks were so prejudicial and grossly improper as to require corrective action by the trial court ex mero motu.
Prior to discussing the merits of each contended error during the prosecutor’s argument to the jury, we must set forth the standard of review to be employed. The defense counsel at trial failed to object to or take exception to any part of the prosecutor’s final argument to the jury. If a party fails to object to a jury argument, the trial court may, in its discretion, correct improper arguments. State v. Johnson, 298 N.C. 355, 259 S.E. 2d 752 (1979). When a party fails to object to a closing argument we must decide whether the argument was so improper as to warrant the trial judge’s intervention ex mero motu. We are therefore reviewing the judge’s action and must decide if he abused his discretion. In State v. Johnson, 298 N.C. 355, 259 S.E. 2d 752 (1979), Chief Justice Branch stated:
In capital cases, however, an appellate court may review the prosecution’s argument, even though defendant raised no objection at trial, but the impropriety of the argument must be gross indeed in order for this Court to hold that a trial judge abused his discretion in not recognizing and correcting ex mero motu an argument which defense counsel apparently did not believe was prejudicial when he heard it.
298 N.C. at 369, 259 S.E. 2d at 761. (Emphasis added.)
* * * *
In North Carolina it is well settled “that counsel is allowed wide latitude in the argument to the jury.” State v. *473 Johnson, 298 N.C. 355, 368, 259 S.E. 2d 752, 761 (1979); see also: State v. Covington, 290 N.C. 313, 226 S.E. 2d 629 (1976). “Even so, counsel may not, by argument or cross-examination, place before the jury incompetent- and prejudicial matters by injecting his own knowledge, beliefs, and personal opinions not supported by the evidence.” (Citations omitted.) State v. Britt, 288 N.C. 699, 711, 220 S.E. 2d 283, 291 (1975). A prosecutor must present the State’s case vigorously while at the same time guarding against statements which might prejudice the defendant’s right to a fair trial.
308 N.C. at 209-211, 302 S.E. 2d at 152-53.
We have carefully and thoroughly reviewed the prosecutor’s closing argument in this case and we find nothing so grossly improper as to require the trial court to take corrective action on its own motion. The challenged portions of the argument were either supported by the evidence or reasonable inferences therefrom, e.g., State v. Pinch, 306 N.C. 1, 292 S.E. 2d 203, cert. denied, 103 S.Ct. 474 (1982), or they were of the same nature as arguments already found by this Court not to be grossly improper per se. E.g., State v. Kirkley, 308 N.C. 196, 302 S.E. 2d 144 (1983); State v. Oliver and Moore, 302 N.C. 28, 274 S.E. 2d 183 (1981); State v. Barfield, 298 N.C. 306, 259 S.E. 2d 510 (1979), cert. denied, 448 U.S. 907 (1980); State v. Britt, 291 N.C. 528, 231 S.E. 2d 644 (1977). This assignment is overruled.
 Defendant’s fourth contention challenges the prosecutor’s remarks during the penalty phase of the trial. During the penalty phase, defendant put on evidence that, while he was in jail awaiting trial, he had become a born-again Christian. During their arguments at this phase, the prosecutor and his assistant vigorously challenged the fact of defendant’s conversion. Among the statements made were the following:
I don’t know lots about religion. I don’t know lots about religion, but I was brought up in a Christian home, and I was always taught by my parents that you must confess your wrong, you must ask for forgiveness. And when I read the scripture, I find words similar to these: “If you will confess me before man, I will acknowledge you before my Father, who is in heaven.” What does that mean? That means if a person has a real, true Christian conversion, he must be honest and sincere with himself and with his fellow man. He must confess his wrong before man and acknowledge that *474before his Christ, and Jesus Christ will acknowledge him before our Heavenly Father. One of the most beautiful things that I ever learned as a youngster was the story of George Washington in chopping down the cherry tree. I don’t have to repeat that. That was a story that I was taught.
I believe that the God that I know and that I have accepted can perform miracles. I believe He did perform miracles. I believe He can change a man’s life. But I say that before He can change a man’s life, that man must confess Him before his fellow man, and then God or Jesus will acknowledge him before God who’s in heaven.
* * * *
[I]f he hasn’t got a true conversion, he can get it. He’s got to ask the Good Master. He’s got to be sincere. He’s got to have a true repentance. It doesn’t take long, but you must be sincere. You must be sincere. There must be a true repentance. You must confess before man, and then Jesus Christ will confess or acknowledge you before God himself.
* * * *
I submit that there is nothing in this man’s background or in his personality that can justify or outweigh what he did. And to this day, as far as we know, there’s been no confession, no remorse.
Defendant maintains that, although he did not object to the above-quoted statements, they were improper comments upon his failure to testify at the penalty phase and hence were egregious enough to require corrective action by the trial court ex mero mo tu. Defendant contends that the court should have instructed the jury during the penalty phase that defendant had the right not to testify.
At the outset, we note that the well-established rules pertaining to the prosecutor’s arguments during the guilt phase of the trial apply equally to the arguments during the penalty phase. State v. Pinch, 306 N.C. 1, 292 S.E. 2d 203. Thus, we must determine if the remarks here were so extreme or prejudicial as to require the trial court to recognize and correct ex mero motu “an argument which defense counsel apparently did not believe was prejudicial when he heard it.” State v. Johnson, 298 N.C. at 369, *475259 S.E. 2d at 761. We have examined the prosecutor’s remarks contextually, and in light of the fact that defendant initially introduced the topic of his religious experience and thus hoped for favorable inferences flowing therefrom, we cannot say that the prosecutor’s exploration of and attack on this subject was so grossly improper as to require the trial court’s acting on its own initiative. See State v. Albert, 303 N.C. 173, 277 S.E. 2d 439 (1981).
 Defendant’s next assignment is likewise addressed to the prosecutor’s argument during the penalty phase. The bulk of defendant’s argument here challenges the prosecutor’s reference to the deterrent effect of the death penalty. It is well settled that criminal defendants in North Carolina may not offer evidence during the penalty phase to show that the capital punishment does not have any deterrent effect. E.g., State v. Cherry, 298 N.C. 86, 257 S.E. 2d 551 (1979). Similarly, we held in State v. Kirkley, 308 N.C. at 215, 302 S.E. 2d at 155, that it was improper for the prosecutor to argue the deterrent effect of capital punishment. Nevertheless, we held in Kirkley that the argument was not so egregious as to require corrective action by the trial judge sua sponte. Id. We likewise do not find the prosecutor’s arguments here to be so offensive as to warrant ex mero motu action by the court.
Of the defendant’s eight remaining assignments of error, seven are addressed to questions previously decided adversely to defendant and defendant so concedes. We have reviewed defendant’s arguments on these questions and are not persuaded that prejudicial error occurred so as to warrant a new trial.
 We thus turn to the final remaining assignment of error dealing with the question of proportionality of the sentence imposed in the instant case. Pursuant to G.S. 15A-2000(d)(2), we are required in every capital case to review the record and determine
(1) whether the record supports the jury’s findings of any aggravating circumstance or circumstances upon which the sentencing court based its sentence of death, (2) whether the sentence was imposed under the influence of passion, prejudice or any other arbitrary factor, and (3) whether the sentence of death is excessive or disproportionate to the *476penalty imposed in similar cases, considering both the crime and the defendant.
State v. Bondurant, 309 N.C. 674, 692, 309 S.E. 2d 170, 181 (1983). The Court thus is charged with conducting a three-pronged test, and after a careful review of the record, we find that the evidence supports the sole aggravating factor found by the jury. See State v. Jackson, 309 N.C. 26, 305 S.E. 2d 703 (1983). In addition, we cannot say that the jury imposed the death penalty “under the influence of passion, prejudice, or any other arbitrary factor.” Id.
The third prong of the statutory test requires the Court to compare similar cases to determine whether the sentence here imposed is disproportionate. The now familiar “pool” of cases, as established in State v. Williams, 308 N.C. 47, 301 S.E. 2d 335, cert. denied, 104 S.Ct. 202 (1983), includes
all cases arising since the effective date of our capital punishment statute, 1 June 1977, which have been tried as capital cases and reviewed on direct appeal by this Court and in which the jury recommended death or life imprisonment or in which the trial court imposed life imprisonment after the jury’s failure to agree upon a sentencing recommendation within a reasonable period of time.
We have recognized, and continue to recognize the gravity of the duty imposed upon us by statute. As we stated in State v. Jackson,
[t]he purpose of proportionality review is to serve as a check against the capricious or random imposition of the death penalty. State v. Hutchins, 303 N.C. 321, 279 S.E. 2d 788 (1981). We repeat that we consider the responsibility placed upon us by N.C.G.S. 15A-2000(d)(2) to be as serious as any responsibility placed upon an appellate court. State v. Rook, 304 N.C. 201, 283 S.E. 2d 732 (1981), cert. denied, 455 U.S. 1038 (1982). In carrying out our duties under the statute, we must be sensitive not only to the mandate of our legislature but also to the constitutional dimensions of our review. Id.
With the magnitude and seriousness of our task in mind, we have reviewed the facts and circumstances of this case arid compared them to the other cases in the proportionality pool. Our careful comparison of the cases has led us to conclude that, while the crime here committed was a tragic killing, “it does not rise to the level of those murders in which we have approved the death sentence upon proportionality review.” State v. Jackson, 308 N.C. at 46, 305 S.E. 2d at 717.
In comparing this case “with other cases in the pool which are roughly similar with regard to the crime and the defendant,” State v. Lawson, 310 N.C. 632, 648, 314 S.E. 2d 493, 503 (1984), we find only two such cases in which the jury found as an aggravating factor that the murder was committed against a law enforcement officer. In State v. Hutchins, 303 N.C. 321, 279 S.E. 2d 788 (1981), we affirmed the jury’s recommendation of the death sentence. In Hutchins, the defendant was convicted of the murders of three police officers, two of which were first-degree murder convictions. The jury found three aggravating factors: (1) the murder was committed to avoid or prevent arrest; (2) the murder was committed against a law enforcement officer while engaged in the performance of his duties; and (3) the murder was part of a course of conduct involving crimes of violence against others. The jury found one mitigating factor: that, at the time of the crimes, defendant was under the influence of a mental or emotional disturbance.
On the other hand, the jury in State v. Abdullah, 309 N.C. 63, 306 S.E. 2d 100 (1983), recommended a life sentence despite having found four aggravating circumstances and only one unspecified mitigating circumstance. The defendant in Abdullah had conspired with five others to commit armed robbery and in the process of carrying out the robbery, defendant shot an officer who had just entered the store. Id.
The facts and circumstances of the instant case simply do not rise to the magnitude of those in Hutchins and Abdullah. Moreover, the great disparity of sentences in those two cases renders any meaningful comparison in this limited pool virtually impossible.
*478Even so, comparing this crime and this defendant to those in other cases in the entire pool in which the death penalty has been affirmed leads us to conclude that the killing in this case, though, as all murders, senseless, was not especially heinous, atrocious or cruel. E.g., State v. McDougall, 308 N.C. 1, 301 S.E. 2d 308, cert. denied, 104 S.Ct. 197 (1983); State v. Pinch, 306 N.C. 1, 292 S.E. 2d 203; State v. Martin, 303 N.C. 246, 278 S.E. 2d 214, cert. denied, 454 S.Ct. 933 (1981). Neither was the crime here of a torturous, sadistic or “bloodthirsty” nature. E.g., State v. Williams, 308 N.C. 47, 301 S.E. 2d 335; State v. Brown, 306 N.C. 151, 293 S.E. 2d 569, cert. denied, 103 S.Ct. 503 (1982); State v. Rook, 304 N.C. 201, 283 S.E. 2d 732. This shooting was not part of a violent course of conduct by defendant. E.g., State v. Lawson; State v. Craig & Anthony, 308 N.C. 446, 302 S.E. 2d 740, cert. denied, 104 S.Ct. 263 (1983); State v. McDougall; State v. Smith, 305 N.C. 691, 292 S.E. 2d 264, cert. denied, 103 S.Ct. 474 (1982); State v. McDowell, 301 N.C. 279, 271 S.E. 2d 286 (1980), cert. denied, 450 U.S. 1025 (1981). Nor was this shooting committed in the perpetration of another felony such as in State v. Craig & Anthony; State v. Williams; State v. Smith, and State v. Rook. Furthermore, there is no evidence that defendant coldly calculated or planned the commission of this crime over a period of time as did the defendant in State v. Barfield, 298 N.C. 306, 259 S.E. 2d 510.
The record in this case reveals that defendant had been drinking on the evening in question, and that he apparently went out in search of one of the Waters sisters with whom he had been earlier and who lived on Woodcock. Officer Enevold noticed a suspicious car in that area and proceeded to investigate. The evidence is unclear as to what happened between the time the officer radioed his message to the station and the time at which he was shot. One eyewitness testified that the officer shone his flashlight into a car parked near the Southern Burglar Alarm Building. The record of this eyewitness’s testimony reveals the following, less than crystal clear, account of the events:
Q. And at that point in time another man approached the officer from behind or from the officer’s side?
A. The officer was looking in the driver’s side, and this person was up on the corner—must have been coming over the fence or something because the officer didn’t see him until he *479hit the curb and that’s when the officer saw him and that’s when I seen him.
Q. At that point in time did the officer turn around and look at him? Could you tell when the officer realized he was there?
A. I can’t really recall that.
Q. Could you see him coming over the fence, the man?
A. It was dark at the time and there was no place for him to have hid there unless he did come over the fence.
The testimony concerning exactly how defendant approached the officer admits of some confusion and is certainly speculative at best. Thus, there is some doubt not only as to defendant’s whereabouts but also as to what he might have been doing just prior to his encounter with the officer. In addition, there is no evidence as to whether the officer drew his gun first, or whether defendant managed to grab the gun from Officer Enevold’s holster in the first instance. The issue of whether or not Officer Enevold was in the process of effecting a valid arrest was not submitted to the jury. Likewise, the aggravating circumstance found in G.S. 15A-2000(e)(4), that the murder “was committed for the purpose of avoiding or preventing a lawful arrest or effecting an escape from custody” was not submitted to the jury. Finally, the entire course of events in this case, from Officer Enevold’s radio communication until Officer Kraus’s message that an officer was down, lasted approximately 80 seconds.
Given the somewhat speculative nature of the evidence surrounding the murder here, the apparent lack of motive, the apparent absence of any simultaneous offenses, and the incredibly short amount of time involved, together with the jury’s finding of three mitigating circumstances tending to show defendant’s lack of past criminal activity and his being gainfully employed, and the unqualified cooperation of defendant during the investigation, we are constrained to hold as a matter of law that the death sentence imposed here is disproportionate within the meaning of G.S. 15A-2000(d)(2). We are therefore required by statute to sentence defendant to life imprisonment in lieu of the death sentence.
The sentence of death is vacated and defendant is hereby sentenced to imprisonment in the State’s prison for the remainder *480of his natural life. Defendant is entitled to credit for days spent in confinement prior to the date of judgment.
Guilt-Innocence Phase: No error;
Sentencing Phase: Death sentence vacated, sentence of life imprisonment imposed.