Defendant is charged with murder. ORS 163.115. The state appeals from a pretrial order excluding other crimes evidence which it wants to offer at trial to prove identity and to impeach defendant in the event that he testifies. The trial court excluded the evidence under OEC 403 for reasons of “unfair prejudice and undue delay in the proceedings.” We reverse and remand.
On December 23,1978, Yvonne Weber was reported missing. In 1985, her remains were found in a rural area near the Cold Springs Reservoir in Umatilla County. They showed possible trauma and contained a .22 caliber bullet. Defendant subsequently was charged in this case with her murder.
The state wants to use witness testimony and defendant’s confession1 to establish these facts: Defendant became acquainted with Weber after he met her in a Umatilla restaurant, which was on his produce sales route. He told Weber’s friend that he found her attractive. A few days before Weber disappeared, she told her mother that a man had offered her a job which paid a good salary and included new clothes and a business car. On December 22, 1978, Weber appeared to be waiting for someone in a Umatilla grocery store. She left the store, walking in the direction of the restaurant, and was not seen again. Defendant’s travel logbook indicated that he had been on another portion of his route, away from Umatilla, on December 22.
The excluded evidence pertains to the murder of another woman and an assault on still another. The state offered testimony that defendant met Diann Remington in December, 1978, that he had often remarked to others that she was pretty, that he had offered her a job which would pay about $20,000 per year, selling women’s clothing and jewelry, and that, when her mother returned home from work on the evening of January 4,1979, she found a note from Remington stating that she would be home later. Remington did not return. On January 26, 1979, her body was discovered in the Horse Heaven Hills area of Benton County, Washington. Her *118death had been caused by multiple stab wounds to the chest. Although defendant presented an alibi defense based on his travel logbook, he was convicted of Remington’s murder.
The state also offered testimony that in January, 1979, defendant met Dina Galassini in a Hermiston restaurant, which was on his route. He told her about a job with a woman’s clothing company which would pay $2,000 monthly and included a company car. On January 26,1979, he set up an evening meeting with Galassini but told her not to tell anyone about the job or about meeting him. That evening, he drove her toward the Horse Heaven Hills in Washington. She protested and told him that she did not want to go there and that she would have to talk to her boyfriend before accepting the job. He became angry, brandished a knife and told her to undress. He then assaulted her with a knife, cutting her breast. He then allowed her to dress and drove her to the area where Remington’s body later was found. He again assaulted her, cutting her wrist. She managed to lock him out of the truck and drove back to Hermiston. At his trial for assaulting Galassini, defendant presented an alibi defense claiming that he had been elsewhere on his route at the time of the assault. He was convicted.
The admissibility of the proffered evidence is governed by OEC 404(3):
“Evidence of other crimes, wrongs or acts is not admissible to prove the character of a person in order to show that the person acted in conformity therewith. It may, however, be admissible for other purposes, such as proof of motive, opportunity, intent, preparation, plan, knowledge, identity, or absence of mistake or accident.”
That is a rule of inclusion that permits the admission of other crimes evidence when it is not offered “solely to prove (1) the character of a person, and (2) that the person acted in conformity therewith.” State v. Johns, 301 Or 535, 548, 725 P2d 312 (1986); see State v. Harvey, 82 Or App 595, 597, 728 P2d 940 (1986).
To be admissible under OEC 404(3), evidence must *119be relevant to an issue at trial, other than character or criminal propensity.2 Further, its probative value must outweigh the danger of unfair prejudice.3 State v. Johns, supra, 301 Or at 549-50. In balancing probative value against the danger of unfair prejudice, a trial court must consider (1) the state’s need for the evidence, (2) the certainty that the other crime was committed and that defendant was the perpetrator, (3) the strength or weakness of the evidence; (4) its possible inflammatory effect on the jury; and (5) how time consuming and distracting proof of the other crimes will be. State v. Johns, supra, 301 Or at 557-58; State v. Collins, 73 Or App 216, 220, 698 P2d 969 (1985). In considering those factors, the court exercises its discretion in ruling on the admissibility of the evidence. State v. Johns, supra, 301 Or at 559.
In this case, the state wants to offer the evidence to prove the identity4 of Weber’s murderer. Other crimes evidence offered to prove identity must show such a similarity, either in the particular manner or the novel means by which the acts were done, as to constitute the distinctive “signature” of the perpetrator. See State v. Manrique, 271 Or 201, 207, 531 P2d 239 (1975); State v. Zimmerlee, 261 Or 49, 52-53, 492 P2d *120795 (1972). The trial court’s determination of the relevancy of the proffered evidence was a legal conclusion which we review for substantial error.5
The trial court found too few significant similarities between the prior crimes evidence and the instant case to establish that the evidence is relevant to prove identity. The court noted that, in all three cases, defendant was acquainted with the victim, that the crimes took place in rural areas and that defendant asserted an alibi defense. However, it found that those circumstances were not unusual in murder and sexual assault cases. The court also noted that the use of the knives in each case was different.6 The court held that the proffered evidence was not relevant to prove identity and, therefore, it did not meet the first test of admissibility.
We agree with the trial court that several of the similar facts relied on by the state are not in themselves uncommon in murder and sexual assault cases. That reduces, but does not eliminate, the weight to be accorded those factors. Yet, a “signature” crime need not be composed solely of unique or novel elements to identify its perpetrator. Just as distinctive signatures may include elements that are not unusual in themselves, a modus operandi or “signature” may *121also include elements which individually have small weight but, in the aggregate, point to a single perpetrator.
We find that the rural locations, defendant’s having made a point of making acquaintances with the victims, his defenses of alibi, the use of knives and numerous other factors cited by the state,7 although, perhaps, not uncommon, weigh strongly in favor of the perpetrator being the same person in each instance. When buttressed by the fact that each of the victims had received a similar, unusual offer for an attractive, nonexistent job, the aggregated factors are strong, as well as relevant, evidence that all three crimes had been committed under the same unique circumstances and that the same person who had murdered Remington and who had assaulted Galassini also murdered Weber. The dissimilarities in the three crimes are not sufficient to defeat the relevance of the other crimes as evidence of identity.8 We conclude that the trial court erred in ruling that the evidence was not relevant to prove identity.
Notwithstanding its ruling that the evidence lacked relevance to prove identity, the trial court proceeded to consider whether the probative value of the proffered evidence outweighed any danger of unfair prejudice. State v. Johns, supra. Trial courts are entitled to deference in the balancing of the probative value of relevant evidence against its potential for unfair prejudice. In this case, however, the trial court’s initial finding of lack of relevance suggests that it found the evidence to have little weight. The court recognized the state’s need for the proffered evidence and found that the certainty *122that the other crimes had been committed by defendant had been established by his convictions. However, the court then held that the prejudicial effect of the evidence far outweighed its relevance and probative value, thus necessitating its exclusion.
Given the certainty that defendant committed the other crimes and their many significant similarities to the crime charged here, the proffered evidence cannot fairly be characterized as weak. Rather, we conclude that it is so strong that it can be outweighed only by a persuasive showing of such unfair prejudice to defendant as substantially to outweigh its probative value.9 That is a determination to be made in the first instance by the trial court. OEC 403; State v. Johns, supra. Accordingly, we reverse and remand to the trial court with instructions to reconsider its order in the light of our conclusion that the state’s other crimes evidence is both relevant and highly probative.
The state also argues that the trial court erred in holding that defendant’s convictions were inadmissible under OEC 609(1) as potential impeachment evidence. The rule has been amended since the trial court’s order, see State v. Dick, 91 Or App 294, 754 P2d 628 (1988), and the amended rule will be in effect on remand. State v. Tucker, 90 Or App 506, 753 P2d 427 (1988); see State v. Carr, 91 Or App 673, 756 P2d 1263 (1988). On remand that issue will be reconsidered under the new rule.
Reversed and remanded for further proceedings not inconsistent with this opinion.
The state’s narrative offer of proof relied in significant part on defendant’s confession to Weber’s murder. Defendant has withdrawn his cross-appeal from the trial court’s ruling admitting the confession.
In State v. Johns, supra, 301 Or at 555, the Supreme Court explained:
“These decisions must be made case-by-case, with the trial judge first determining whether the evidence has any probative value under OEC 401 as applied to [an issue other than character] under OEC 404(b), then deciding whether the evidence has any prejudicial effect outweighing its probativity under OEC 403.” (Footnote omitted.)
OEC 401 provides:
“ ‘Relevant evidence’ means evidence having any tendency to make the existence of any fact that is of consequence to the determination of the action more probable or less probable than it would be without the evidence.”
In State v. Johns, supra, 301 Or at 549-550, the Supreme Court commented:
“Even if the evidence is relevant for some purpose other than proving a propensity to commit certain acts, the trial judge’s task is not completed. The judge still must decide whether to admit the evidence and must articulate reasons for that decision on the record. In other words, in deciding issues under OEC 404(3) the trial court must apply OEC 403, * * *”
OEC 403 states:
“Although relevant, evidence may be excluded if its probative value is substantially outweighed by the danger of unfair prejudice, confusion of the issues, or misleading the jury, or by consideration of undue delay or needless presentation of cumulative evidence.”
The state’s contention during oral argument in this court that the evidence was also offered to prove motive, intent and preparation is not supported by the record.
An appellate court is not bound by a trial court’s conclusions of law. See State v. Warner, 284 Or 147, 158-159, 585 P2d 681 (1978). The trial court made its rulings on the same record available to this court and was in no better position than we are to determine the relevance of the evidence offered by the state. We also note that the ruling was not made in the context of a trial, in which a trial court’s assessments of need and the potential for unfair prejudice would be better informed than ours and, thus, entitled to greater deference. We addressed this issue in State v. Browder, 69 Or App 564, 567, 687 P2d 168 (1984):
“A pre-trial ruling on the admissibility of evidence is necessarily more difficult for the trial court, because it lacks a full context on which to base its decision. Although the parties often make elaborate offers of proof, sometimes to the point of essentially presenting their whole case, that remains, in many cases, an awkward and inefficient way to create a context to enable a trial judge to rule on the matter. In most cases, only proffered evidence which carries an unusual potential for prejudice should be ruled on before trial. Preferably evidence should be presented and ruled on in the normal course of the trial rather than within the permissive ambit of an omnibus hearing under ORS 135.037(3).” (Emphasis in the original.)
In view of Gallasini’s resistance and her escape from defendant, the trial court appears to have placed undue emphasis on the location of the victims’ wounds as a dissimilar factor. Galassini received cuts on her breast and wrist rather than stab wounds in the chest, as did Remington and Weber. Accordingly, we accord the location of the wounds less weight than the fact that a knife was used in all three crimes.
The state’s evidence also noted the similarities in the marital status and appearance of the three victims (race, body build, hairstyle and facial features); that defendant’s acquaintance with each victim had been initially related to defendant’s job; that he had made remarks as to the attractiveness of all three victims and his sexual desire for them; that defendant had arranged appointments with the victims to discuss his job offers; that in both the Galassini assault and the Weber murder he used his company vehicle; that he had sexual relations or attempted to with each victim; that in each case the victim was attacked or murdered after a sexual or attempted sexual encounter; that defendant buried both murder victims in shallow graves; that he later returned to the scene of both murders; that defendant made continued references to both murder victims after their disappearances; and, in all three cases, defendant attempted to establish that he was elsewhere on his sales route on the dates of the crimes (in both murder cases he prepared false log entries to establish an alibi).
As argued by the state, differences in the Galassini assault can be accounted for by her resistance and escape from defendant.
Although the trial court included “undue delay” as a ground for exclusion, nothing in the record explains the court’s conclusion. Trial courts must make findings on the record to support their conclusions and rulings. The findings are necessary to permit this court to review the exercise of discretion. See State v. Lutz, 306 Or 499, 760 P2d 249 (1988).