Defendant contends the trial court erred in excusing for cause certain prospective jurors who indicated they could not return a verdict of guilty knowing such verdict would necessitate imposition of a death sentence.
We note initially that in his brief defendant names no specific juror he contends was improperly challenged for cause. He apparently challenges the phraseology of the questions propounded by the district attorney to prospective jurors McCall and McDonald. The district attorney asked these and other jurors whether they were “opposed to it” (capital punishment) or “felt it was necessary.” The initial responses of these jurors were rather equivocal. Nevertheless, despite the imprecise questions of the district attorney, we conclude that all jurors who were excused for cause, including jurors McCall and McDonald, eventually indicated, frequently only after further inquiry by the court, that they were irrevocably committed to vote against a verdict carrying the death penalty regardless of the facts and circumstances that might be revealed by the evidence.
With respect to jury selection in capital cases, we have interpreted Witherspoon v. Illinois, 391 U.S. 510, 20 L.Ed. 2d 776, 88 S.Ct. 1770 (1968), to mean that veniremen may not be challenged for cause simply because they voice general objections to the death penalty or express conscientious or religious scruples against its infliction; but veniremen who are unwilling to consider all of the penalties provided by law and who are irrevocably committed, before the trial has begun, to vote against the death penalty regardless of the facts and circumstances that might emerge in the course of the trial may be challenged for cause on that ground. State v. Monk, 286 N.C. 509, 212 S.E. 2d 125 (1975) ; State v. Honeycutt, 285 N.C. 174, *707203 S.E. 2d 844 (1974) ; State v. Crowder, 285 N.C. 42, 203 S.E. 2d 38 (1974). In light of these principles, we hold that the prospective jurors here in question were properly excused for cause. Defendant’s first assignment of error is overruled.
Even so, we again emphasize that counsel involved in the trial of capital cases, particularly prosecuting attorneys, when interrogating veniremen concerning their scruples and attitudes toward capital punishment, should employ questions which incorporate the terminology required by Witherspoon and Monk and insist on unequivocal answers. “Since Witherspoon has so clearly specified the ultimate question that must be answered, the voir dire examination of prospective jurors should be based on questions phrased in Witherspoon language. Unless this course is followed, new trials will often be necessary in cases otherwise free from prejudicial error.” State v. Monk, supra.
This brings us to the question whether defendant was denied a fair trial by prejudicial conduct of the district attorney. A few of the alleged improprieties assigned as error are discussed below.
1. The prosecutor inquired whether or not defendant considered Carolyn Blackwell, the wife of the deceased, to be his girl friend. The following exchange then occurred before the jury:
“Q. [By the district attorney:] Isn’t she your girl friend?
A. [By defendant:] Yes, sir.
Q. She was your girl friend on the 3rd of May and prior thereto; isn’t that right?
A. Yes, sir.
Q. She’s discussed this case with you in detail while you sat on death row for the past year; hadn’t she?
Exception No. 85.
A. No, sir.
A. No, sir.
*708Q. She’s been up there frequently and talked with you on death row about this case, after you were convicted the last time?
Exception No. 86.
Me. Diehl: Objection.
The Couet: Sustained.”
At this point the court directed the jury to retire to the jury room, and in its absence defense counsel moved for a mistrial on the ground that the foregoing questions were so prejudicial that a fair trial by this jury was no longer possible. The trial judge stated: “I’m very much concerned about this. This jury should not know that he has been previously convicted and sentenced to death. I will see counsel in Chambers.” The judge retired to chambers to discuss the matter with the district attorney and defense counsel. Upon returning to the courtroom the trial judge, with the consent of defense counsel, recalled the’ jury and instructed it that defendant previously had been convicted of first degree murder and sentenced to death but his conviction had been reversed by the Supreme Court of North Carolina so that the present trial was entirely new. The judge instructed the jury not to consider the prior trial and not to be influenced to any extent by defendant’s prior conviction. Following such instruction defense counsel stated that he desired no further instructions and that his motion for mistrial was withdrawn. Subsequently, upon completion of the trial and during its charge to the jury, the court again instructed the jury to disregard defendant’s prior trial and conviction, not to hold it against him, and to render their verdict solely upon new evidence offered at this particular trial.
2. In his argument to the jury the district attorney, asserted that Clarence Blackwell, the deceased, had a right to defend himself in his own home. This evoked the following exchange:
“Me. Diehl [defense counsel]: Objection, your Honor. He keeps referring to the man’s right in his own home. Evidence is that he was separated from his wife for a long period of time. He goes over it and over it.
Me. Beht [district attorney] : It is his home.
The Couet: Well, as to that, the Court is not going to give any instructions to that effect. The evidence tends *709to show that they were separated and that the defendant was an invitee of the woman who lived there. Sustained.
Mr. Britt: Tell you what, I left my wife to go to Washington a couple of weeks ago and I was gone for nearly a week. I was separated from her.
Mr. Diehl: Objection.
Mr. Britt: When I came back I didn’t expect to find nobody else to be in there and I expect I done something about if I found anybody there.”
3. During closing argument the district attorney said: “I just don’t believe in my own heart and mind that Jimmy Britt was cut as bad as he says he was. I don’t believe he was cut the way he was. A man who kills another can do anything, I believe, if he wants to. Just take a knife and whack across the stomach and once across the bottom and once across the leg and once across the arm, and report into the hospital. What better way to cover it up, Ladies and Gentlemen of the Jury?” There is no evidence, inferential or otherwise, to support this argument.
4. During his closing argument the district attorney referred to the fact that Mrs. Blackwell was not called to testify for defendant. In doing so he stated that the reason for her failure to testify was “because she hasn’t got what it takes to ‘perjwre herself the way Jimmy Britt swore to you.” Defendant’s objection to this statement was sustained, whereupon the district attorney immediately asked again, “Where is Carolyn ?” At this point the trial judge instructed the jury not to consider the remarks about perjury.
5. During the redirect examination of David Blackwell, a State’s witness and the son of the deceased, the district attorney repeatedly asked leading questions, to which defendant’s objections were sustained. The trial judge stated that he considered the questions to be leading notwithstanding the tender age of the witness. Despite the court’s admonition not to lead the witness, the prosecutor continued to do so. After the court sustained defendant’s objection to still another question as leading, the district attorney stated: “It was meant to be.”
6. During further redirect examination of the witness Blackwell, and during his closing argument, the district attorney implied and stated that the possible inconsistencies in the wit*710ness’s testimony could be attributed to the fact that he had been “brainwashed” while visiting defendant during his stay in prison and during meetings arranged by Mrs. Blackwell with defendant’s half-sister. There is no evidence in the record to support this statement. At one point during the recross examination of this witness, counsel for defendant asked whether anyone had told him to do anything but tell the truth. The objection of the district attorney was overruled and the witness answered in the negative. The district attorney retorted: “Somebody told him something.”
7. During final argument the district attorney repeatedly referred to the knife used by the deceased as “a little, old pocketknife” or a “penknife.” The knife was not offered in evidence and its size is not shown by the record. Defendant’s objections to such references to the knife were sustained.
 Every person charged with a crime has an absolute right to a fair trial. By this it is meant that he is entitled to a trial before an impartial judge and an unprejudiced jury in keeping with substantive and procedural due process requirements of the Fourteenth Amendment. Rogers v. Richmond, 365 U.S. 584, 5 L.Ed. 2d 760, 81 S.Ct. 735 (1961) ; Lisenba v. California, 314 U.S. 219, 86 L.Ed. 166, 62 S.Ct. 280 (1941) ; State v. Chamberlain, 263 N.C. 406, 139 S.E. 2d 620 (1965) ; State v. Carter, 233 N.C. 581, 65 S.E. 2d 9 (1951). It is the duty of both the court and the prosecuting attorney to see that this right is sustained. State v. Monk, supra; State v. Thompson, 278 N.C. 277, 179 S.E. 2d 315 (1971) ; State v. Barefoot, 241 N.C. 650, 86 S.E. 2d 424 (1955) ; State v. Phillips, 240 N.C. 516, 82 S.E. 2d 762 (1954) ; State v. Correll, 229 N.C. 640, 50 S.E. 2d 717 (1948), cert. denied 336 U.S. 969, 93 L.Ed. 1120, 69 S.Ct. 941 (1949) ; State v. Howley, 220 N.C. 113, 16 S.E. 2d 705 (1941). To these ends there are rules of practice and decorum with which all counsel involved in the trial of criminal cases must abide.
The district attorney owes honesty and fervor to the State and fairness to the defendant in the performance of his duties as a prosecutor. His duties are more fully stated in 63 Am. Jur. 2d, Prosecuting Attorneys, § 27 (1972), as follows:
“The public interests demand that a prosecution be conducted, with energy and skill, but the prosecuting officer should see that no unfair advantage' is taken of the accused. It is as much his duty to see that a person on trial is not *711deprived of any of his statutory or constitutional rights as it is to prosecute him for the crime with which he may be charged. Nonetheless, zeal in the prosecution of criminal cases is to be commended and not condemned. If convinced of the defendant’s guilt, the prosecuting attorney should, in an honorable way, use every power that he has to secure the defendant’s conviction. At the same time, it is his duty to hold himself under proper restraint and avoid violent partisanship, partiality, and misconduct which may tend to deprive the defendant of the fair trial to which he is entitled, and it is as much his duty to refrain from improper methods calculated to bring about a wrongful conviction as it is to use every legitimate means to bring about a just one.”
See Berger v. United States, 295 U.S. 78, 79 L.Ed. 1314, 55 S.Ct. 629 (1935). Accord, State v. Stegmann, 286 N.C. 638, 213 S.E. 2d 262 (1975) ; State v. Monk, supra; State v. Westbrook, 279 N.C. 18, 181 S.E. 2d 572 (1971), vacated on other grounds, 408 U.S. 939, 33 L.Ed. 2d 761, 92 S.Ct. 2873 (1972) ; 23A C.J.S., Criminal Law §§ 1081, 1083 (1961).
[3, 4] The argument of counsel is left largely to the control and discretion of the presiding judge and counsel is allowed wide latitude in the argument of hotly contested cases. State v. Stegmann, supra; State v. Monk, supra; State v. Thompson, supra; State v. Seipel, 252 N.C. 335, 113 S.E. 2d 432 (1960) ; State v. Barefoot, supra; State v. Little, 228 N.C. 417, 45 S.E. 2d 542 (1947). Counsel may argue to the jury the facts in evidence and all reasonable inferences to be drawn therefrom and the law relevant thereto. State v. Noell, 284 N.C. 670, 202 S,E. 2d 750 (1974) ; State v. Conner, 244 N.C. 109, 92 S.E. 2d 668 (1956) ; State v. Willard, 241 N.C. 259, 84 S.E. 2d 899 (1954). Language may be used consistent with the facts in evidence to present each side of the case. State v. Monk, supra.
[5, 6] 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. State v. Monk, supra; State v. Noell, supra; State v. Phillips, supra; State v. Dockery, 238 N.C. 222, 77 S.E. 2d 664 (1953). Nor may counsel ask impertinent and insulting questions which he knows will not elicit competent or relevant evidence but are designed simply to badger and humiliate the witness. State v. Daye, 281 N.C. *712592, 189 S.E. 2d 481 (1972) ; State v. Wyatt, 254 N.C. 220, 118 S.E. 2d 420 (1961). The district attorney should refrain from characterizations of defendant which are calculated to prejudice him in the eyes of the jury when there is no evidence from which such characterization may legitimately be inferred. See State v. Christopher, 258 N.C. 249, 128 S.E. 2d 667 (1962) ; State v. Wyatt, supra; State v. Bowen, 230 N.C. 710, 55 S.E. 2d 466 (1949). “Prosecuting attorneys are in a very peculiar sense servants of the law. [Citation omitted.] They owe the duty to the State which they represent, the accused whom they prosecute, and the cause of justice which they serve to observe the rules of practice created by law to give those tried for crime the safeguards of a fair trial.” State v. Phillips, supra.
While G.S. 84-14 confers upon counsel the right to argue to the jury the whole case as well of law as of fact, “argument is not without its limitations. The trial court has a duty, upon objection, to censor remarks not warranted by either the evidence or the law, or remarks calculated to mislead or prejudice the jury. [Citations omitted.] If the impropriety is gross it is proper for the court even in the absence of objection to correct the abuse ex mero motu, State v. Smith, 240 N.C. 631, 83 S.E. 2d 656 (1954).” State v. Monk, supra. Accord, State v. Miller, 271 N.C. 646, 157 S.E. 2d 335 (1967).
Application of these principles to the present case compels the conclusion that the district attorney’s courtroom tactics transcend the bounds of propriety and fairness. More specifically, we hold that the improprieties enumerated in paragraphs numbered 1, 2 and 3 constitute prejudicial error requiring a new trial.
 With respect to the challenged cross-examination of defendant shown in paragraph numbered 1, the district attorney has a right and duty in a homicide prosecution to cross-examine a defendant who testifies in his own defense, State v. Ross, 275 N.C. 550, 169 S.E. 2d 875 (1969), cert. denied 397 U.S. 1050, 25 L.Ed. 2d 665, 90 S.Ct. 1387 (1970) ; State v. Wentz, 176 N.C. 745, 97 S.E. 420 (1918), but such cross-examination must be fair at all times. Cross-examination by which the prosecutor places before the jury inadmissible and prejudicial matter is highly improper and, if knowingly done, unethical. State v. Daye, supra; State v. Phillips, supra; American Bar Association, Project on Standards for Criminal Justice, Standards Relating to the Prosecution Function and the Defense Function, §§ 56, 57 *713at 38-39 (1971) ; American Bar Association, Codé of Professional Responsibility, Canon 7 (1974).
The trial judge attempted to correct this transgression by sustaining defendant’s objection and twice instructing the jury to disregard defendant’s prior conviction and return a verdict based solely upon the evidence presented in the present trial. Ordinarily, counsel’s improper conduct may be cured by such action by the trial court, see State v. Sparrow, 276 N.C. 499, 173 S.E. 2d 897 (1970) ; State v. Correll, 229 N.C. 640, 50 S.E. 2d 717 (1948), since the presumption is that jurors will understand and comply with the instructions of the court. State v. Self, 280 N.C. 665, 187 S.E. 2d 93 (1972) ; State v. Long, 280 N.C. 633, 187 S.E. 2d 47 (1972). We have recognized, however, that some transgressions are so gross and their effect so highly prejudicial that no curative instruction will suffice to remove the adverse impression from the minds of the jurors. See State v. White, 286 N.C. 395, 211 S.E. 2d 445 (1975) ; State v. Hines, 286 N.C. 377, 211 S.E. 2d 201 (1975) ; State v. Roach, 248 N.C. 63, 102 S.E. 2d 413 (1958) ; State v. Smith, 240 N.C. 631, 83 S.E. 2d 656 (1954) ; State v. Dockery, supra; State v. Eagle, 233 N.C. 218, 63 S.E. 2d 170 (1951) ; State v. Hawley, 229 N.C. 167, 48 S.E. 2d 35 (1948) ; State v. Little, supra. A fair consideration of the principles established and applied in these cases constrains us to hold that no instruction by the court could have removed from the minds of the jurors the prejudicial effect that flowed from knowledge of the fact that defendant had been on death row as a result of his prior conviction of first degree murder in this very case. The probability that the jury’s burden was unfairly eased by that knowledge is so great that we cannot assume an absence of prejudice. State v. Hines, supra. We hold the challenged questions by the district attorney were highly improper and incurably prejudicial.
 In paragraph numbered 2 the repeated argument of the district attorney that the deceased had a right to defend himself “in his own home” was unsupported by the evidence and placed before the jury legal principles not applicable to the case. Although the court sustained defendant’s objection, stating that the evidence tended to show that the deceased and his wife were separated and that defendant was an invitee of Mrs. Blackwell, the district attorney quite effectively overruled the court and continued to argue the point. This violates the rule that counsel may not argue principles of law not relevant to the case. State *714 v. Crisp, 244 N.C. 407, 94 S.E. 2d 402 (1956). The courteous rulings of the able and patient trial judge had no deterring effect upon the prosecutor. His conduct in this manner was disrespectful to the court and prejudicial to defendant.
 In paragraph numbered 8 the argument of the district attorney that defendant, after he shot and killed Clarence Blackwell, cut himself with a knife to cover up the murder is wholly unsupported by the evidence or by any facts or circumstances permitting such an inference. This violates the rule that counsel may not travel outside the record and place before the jury an incompetent and prejudicial theory of the case grounded wholly on personal beliefs and opinions not supported by the evidence. State v. Monk, supra; State v. Noell, supra. This improper argument was not brought to the attention of the court by timely objection so as to afford the court an opportunity to correct the transgression in the charge. Even so, the fact that it occurred without correction only adds to the biased atmosphere created by overzealousness of the prosecution.
The matters disclosed by numbered paragraphs 4, 5, 6 and 7 further accentuate the cumulative effect of the district attorney’s excessive infringement upon defendant’s constitutional right to a fair trial at the hands of an unprejudiced jury.
The balance between the dual roles of the district attorney as impartial representative of the people and zealous advocate for the State is a delicate one. Yet according fair treatment to the defendant does not require a compromise of advocacy, for zealousness and fairness are complementary qualities in an effective prosecution where the goal to be achieved is what it should be — a just conviction of the guilty. See H. B. Vess, “Walking a Tightrope: A Survey of Limitations on the Prosecutor’s Closing Argument,” 64 Journal of Criminal Law and Criminology 23 (March 1973). The district attorney who prosecuted this case most likely committed the excesses noted by an overzealous desire to secure the conviction of an accused he believed to be guilty of murder. In that connection the following admonition of Justice Ervin, speaking for this Court in State v. Warren, 235 N.C. 117, 68 S.E. 2d 779 (1952), is most appropriate:
“Ministers of the law ought not to permit zeal in its enforcement to cause them to transgress its precepts. They should remember that where law ends, tyranny begins.”
*715We deem it unnecessary to discuss other assignments since the errors alleged may not recur on retrial.
For the reasons stated the judgment below is vacated and the case remanded to the Superior Court of Robeson County for a