In his first assignment of error, defendant contends that the trial court erred in failing to grant his motion to dismiss the murder charge. We agree.
“Upon the defendant’s motion for judgment of nonsuit in a criminal action, the question for the court is whether there is substantial evidence of each essential element of the offense charged, or of a lesser offense included therein, and of the defendant’s being the perpetrator of such offense. ... In making this determination, the evidence must be considered in the light most favorable to the State and the State is entitled to the benefit of every reasonable inference to be drawn from it. . . .
“The test of the sufficiency of the evidence to withstand the motion for judgment of nonsuit is the same whether the evidence is circumstantial, direct or both. . . . There is substantial evidence of each element of the offense charged, . . . and of the identity of the defendant as the perpetrator of it if, but only if, interpreting the evidence in accordance with the foregoing rule, the jury could draw a reasonable inference of each such fact from the evidence. ... If, on the other hand, the evidence so considered, together with all reasonable inferences to be drawn therefrom, raises no more than a suspicion or a conjecture, either that the offense charged in the indictment, or a lesser offense included *237therein, has been committed or that the defendant committed it, the evidence is not sufficient and the motion for judgment of non-suit should be allowed.” [Citations omitted.] State v. Vestal, 278 N.C. 561, 180 S.E. 2d 755 (1971), cert. denied, 414 U.S. 874, 94 S.Ct. 157, 38 L.Ed. 2d 114 (1973); see also State v. Powell, 299 N.C. 95, 261 S.E. 2d 114 (1980); State v. Smith, 40 N.C. App. 72, 252 S.E. 2d 535 (1979).
The rule, thus stated, proves more difficult in application than in formulation. Nearly a century ago, our courts recognized that the question “. . . whether there is sufficient evidence to go to the jury ... is often [an] embarrassing one to the courts and probably gives them as much trouble as any question that comes before them . . . .” State v. Gragg, 122 N.C. 1082, 30 S.E. 306 (1898). Twentieth century courts have made little progress toward resolving the problem and cases decided since Gragg lack consistent analyses and results. The difficulty of applying the standard consistently to the varying facts of each case increases where evidence of the defendant’s guilt is purely circumstantial. This is so because determining the significance of circumstantial evidence requires the trier of fact to infer the presence of a disputed fact from an offered fact, a logical step not required in evaluating direct evidence.
Perhaps it is this additional step which explains the confusion in decisions concerning sufficiency of the evidence. The lack of consistency in the case law begs for the construction of some test or guideline around which both defense and prosecution attorneys could build their cases. Our analysis of the cases and the problem before us, however, convinces us that such a standard, while desirable, would not be sufficiently flexible and is certainly not supported by precedent.
The first area of confusion in decided cases concerns the quantum of proof that the state must present in order to survive a defendant’s motion to dismiss. Earlier cases required that the state must present evidence inconsistent with any hypothesis other than guilt. State v. Harvey, 228 N.C. 62, 44 S.E. 2d 472 (1947). This language was overruled, at least formally, in State v. Stephens, 244 N.C. 380, 93 S.E. 2d 431 (1956). In that case the court held that the state need only present substantial evidence of all material elements of the offense to overcome a motion to *238dismiss. “To hold that the court must grant a motion to dismiss unless, in the opinion of the court, the evidence excludes every reasonable hypothesis of innocence would in effect constitute the presiding judge the trier of facts.” Id. While the rule appears sound and well-reasoned, it is unclear whether introduction of the new standard has made a significant difference in the outcome of cases. See, e.g., State v. Lee, 294 N.C. 299, 240 S.E. 2d 449 (1978), in which the court noted that the facts presented by the state “excited suspicion in the just mind that he is guilty, but such view is far from excluding the rational conclusion that some other unknown person may be the guilty party . . .” citing State v. Goodson, 107 N.C. 798, 12 S.E. 329 (1890).
In addition to the inconsistent language concerning the level of proof required of each material element of the crime, the cases fail to specify how much evidence the state must produce that the defendant is the perpetrator of the crime. The modern “test” states only that there must be substantial proof of each element of the crime and that the defendant committed the act. There appears to be no logical reason to require less than “substantial” proof that defendant is the perpetrator, however, despite the lack of authority on the subject.
The difficulty in labelling the required level of proof that defendant committed the crime touches only the surface of the problem presented upon a motion to dismiss. The real problem lies in applying the test to the individual facts of a case, particularly where the proof is circumstantial. One method courts use to assist analysis is to classify evidence of guilt into several rather broad categories. Although the language is by no means consistent, courts often speak in terms of proof of motive, opportunity, capability and identity, all of which are merely different ways to show that a particular person committed a particular crime. In most cases these factors are not essential elements of the crime, but instead are circumstances which are relevant to identify an accused as the perpetrator of a crime. See, e.g., State v. Palmer, 230 N.C. 205, 52 S.E. 2d 908 (1950); State v. O’Neal, 187 N.C. 22, 120 S.E. 817 (1924); Brandis, North Carolina Evidence § 83 (2d rev. ed. 1982). While the cases do not generally indicate what weight is to be given evidence of these various factors, a few rough rules do appear. It is clear, for instance, that evidence of either motive or opportunity alone is insufficient to carry a *239case to the jury. State v. White, 293 N.C. 91, 235 S.E. 2d 55 (1977) (the victim lived in a mobile home adjacent to the motel where defendant lived; defendant, a black man, frequently visited the victim; a black man was seen running away from the mobile home on the evening of the killing; there was blood on the carpet of defendant’s motel room, and a knife similar to the murder weapon was found in defendant’s room); State v. Cutler, 271 N.C. 379, 156 S.E. 2d 679 (1967) (defendant was seen driving to the victim’s house twice on the day of the killing and that his truck was parked in the victim’s yard; defendant, who had been drinking heavily, returned home on the day of the killing with a deep head wound; and a search of defendant’s room revealed a bloody pocket knife with chest hairs similar to the victim’s stuck on the blade); see also State v. Hendrick, 232 N.C. 447, 61 S.E. 2d 349 (1950); 4 N.C. Index 3d, Criminal Law § 106.2.
When the question is whether evidence of both motive and opportunity will be sufficient to survive a motion to dismiss, the answer is much less clear. The answer appears to rest more upon the strength of the evidence of motive and opportunity, as well as other available evidence, rather than an easily quantifiable “bright line” test. For instance, in State v. Furr, 292 N.C. 711, 235 S.E. 2d 193, cert. denied, 434 U.S. 924, 98 S.Ct. 402, 54 L.Ed. 2d 281 (1977), defendant threatened ex-wife repeatedly, tried to hire others to kill her, possessed a garage door opener to her home and lived within five minutes of her home. Our Supreme Court held that this evidence was sufficient only to raise a suspicion or conjecture as to defendant’s guilt and that defendant’s motion to dismiss should have been allowed. Likewise, the evidence was deemed insufficient in the following cases: State v. Lee, supra (defendant had beaten and threatened the victim, who was his former lover, was aware she had had an affair with a neighbor, owned a gun and lived in the same mobile home with her, a few miles from the spot where the victim was found shot to death); State v. Gragg, supra (defendant bore grudges against both victims, had threatened them, possessed dynamite of the kind used in the murder and was seen within half a mile of the victims’ home on the day of the killing).
It seems impossible therefore, to glean from the existing cases any clear, bright-line test by which it can be accurately and consistently determined when the state has presented sufficient *240substantial circumstantial evidence of identity of the perpetrator to survive a defendant’s motion to dismiss. Nor does the nature of the problem lend itself to construction of such a test. In many ways the problem of determining when “substantial” evidence of identity has been presented is similar to the problem of determining whether evidence is relevant and therefore admissible. To be relevant, evidence must tend however slightly, to prove existence of a disputed fact. To analogize, the state’s evidence must tend substantially to prove the disputed fact that defendant is the perpetrator. The levels of proof required to establish relevancy and substantial evidence of identity are of course different, but in both cases inferences from an established fact must be drawn to establish a disputed fact, based on established rules of physics or common experience. Brandis, supra, § 81. Brandis has warned against attempting to erect bright-line tests for determining relevancy of evidence.
Indeed, the variety of possible fact situations is so nearly infinite that, as the Court has recognized, no precise rule of general application can be formulated. ... in the absence of a clearly applicable and authoritative precedent, problems of relevancy can be resolved only by logic and experience, hopefully leavened with a modicum of common sense. Since the first of these three elements is subject to refined disputation and the other two vary rather widely as between judges, the combination does not guarantee unanimity or even consensus in specific situations. But no better approach is available or is likely to become available through ingeniously contrived, judicially enunciated “test” or definitions; nor is the omnipotent computer likely to be of aid.
Id. § 78, 290 n. 22.
Recognizing that existing case law and the necessity to retain flexibility are aligned against temptation to construct a bright-line test, we are left with the standard of reviewing motions to dismiss in cases such as the one now before us “in the light of all the circumstances,” which at least has the blessings of precedent, although it lacks predictability. We turn, therefore, to an analysis of the state’s evidence in the case before us, to determine if the state presented substantial evidence that defendant committed the crime. We conclude the state did not meet its bur*241den and that the motion to dismiss should have been allowed. The only substantial evidence linking defendant to the crime consisted of the victim’s keys which were found in defendant’s pockets.
While the state argues otherwise, we conclude that the evidence of the results of tests of blood taken from the victim’s apartment and from the rubber glove are of such small positive probative value that it did not serve to identify defendant as the perpetrator. It is well established that blood tests are “highly probative negatively” but have “minimal” positive probative value. That is, while the tests may accurately determine that a person could not have been the source of a certain blood type, the tests cannot accurately establish that a particular, single individual was the source of the blood. State v. Fulton, 299 N.C. 491, 263 S.E. 2d 608 (1980); Annot., 2 A.L.R. 4th 500 (1980 & 1983 Supp.). The evidence linking defendant to the Princess Street break-in and the glove found on the porch of the home there was so nebulous as to lack probative value. Ms. Newton was unable to identify defendant as the man she saw climb out of the Princess Street home; nor did she know how the glove was deposited on the porch. Further, there was no evidence that when arrested, defendant had any wounds from which he could have left blood at the scene of the crime.
The fact that the knife found near the spot where defendant was arrested fit the sheath found in the victim’s apartment is of little probative value. First, the inference must be drawn that the knife belonged to defendant only because it was found near where defendant was apprehended. Second, the inference must be drawn that the knife found near defendant belonged to the sheath found in Hamilton’s apartment. Such evidence is far too tenuous to be considered as substantial proof of anything.
Evidence that the victim’s keys were found in defendant’s pocket tends to show that defendant had access to the victim’s apartment and therefore had the opportunity to murder him, but does not constitute substantial evidence of motive.
In sum, the evidence taken in the light most favorable to the state at the most shows only defendant had an opportunity to kill the victim. As discussed above, evidence of opportunity alone is insufficient to survive a defendant’s motion to dismiss. A careful review of all the circumstances shown by the state’s evidence in *242this case leads us to the conclusion that the state raised no more than a suspicion that defendant murdered Hamilton, and that, therefore, defendant’s motion to dismiss should have been allowed.
Defendant has raised numerous other exceptions and assignments of error which we need not address in light of our holding that defendant’s conviction may not stand. For the reasons stated, the judgment below must be and is
Reversed and vacated.
Judge Johnson concurs.
Chief Judge VAUGHN dissents.