Appellants were convicted of robbing an Oakland California Post Office on December 15, 1976. 18 U.S.C. § 2114. Roderick Smith complains that there was insufficient evidence to justify his conviction, and that an expert in the field of psychology should have been permitted to testify as to certain scientific principles of perception and memory, as they pertain to eyewitness identification. Henry Smith joins in urging these two issues, and in addition, contends that his trial should have been severed from his co-defendant.
On the date of the offense, a robber pointing a handgun appeared in the lobby of the Post Office and shouted, “Don’t anybody move.” A companion, wearing a mask that was described by one witness as a scarf covering the bottom half of his face, vaulted the service counter and picked up an envelope containing the day’s cash receipts. Both robbers then exited the building.
Postal employee, Patrifeia Campbell, described the gun-wielding robber to investigators as stocky, but not fat, a dark-skinned Negro in his late 20s, about 5'8" to 5'10" tall, having broad shoulders, medium, natural hair style, clean-shaven, and wearing a cap. She said he wore dark clothes, and that she felt that she had seen him somewhere before. His nose and ears assisted her in her identification, and she readily pointed out Roderick Smith in open court as the man who had the gun. One month after the robbery, Campbell selected Roderick’s photo from a spread and indicated that he was one of the robbers.
Betty Gaither, another postal employee, testified that the robber carrying the gun was stocky, and wore a cap. She selected a photo of Roderick as a picture of a person who “looked like” the robber with the gun. She stated that his eyes, nose and mouth were similar, and that he had eyes that looked like her brother’s.
*1363A customer in the Post Office, Elmer Frugoli, stated that Roderick’s nose looked familiar, and in some other ways, he corroborated descriptions given by Campbell and Gaither.
A careful review of all of the evidence supporting identification of Roderick, leaves little question in our minds that the jury had a substantial basis for concluding that he was properly identified as the robber who first appeared in the lobby.
The identification testimony concerning Henry Smith is not as strong as that which addressed itself to his companion; but, after giving due consideration to the testimony of the one eyewitness who seemed positive in her assurances that she had pointed out the right man, we conclude that Henry was given a fair trial and was properly convicted. Mrs. Campbell testified that the second robber was lighter in complexion, small and slender, and that he kept a scarf over the lower portion of his face. She stated that Henry “really looks like him.” Later, she selected a photo of Henry from a spread, after masking the lower part of the face with a card.
In a quest to be as sure as it can that the right person is before the Court, the fact-finder must rely heavily upon the eyewitnesses who saw the events. Consideration must be given to the opportunity that the witness had to make observation, as compared with the opportunity of other witnesses whose testimony is less certain; the lapse of time between the occurrence of the crime and the first confrontation, and whether the initial description given investigators by the witness compares favorably with the person accused. United States v. Levi, 405 F.2d 380, 383 (4th Cir. 1968). Any emotion, such as extreme fright, experienced by the witness during the criminal ordeal which might lessen the value of his later selection of the accused as the culprit ought to be weighed carefully.
We still cling to the notion that the testimony of one witness, if solidly believed, is sufficient to prove the identity of a perpetrator of crime. 18 U.S.C. § 3502; 7 Wigmore, Evidence § 2034 p. 259. When there is some corroboration of that testimony, even greater reason exists for upholding the verdict of a jury which accepted it.
In this case, Campbell had no hesitation in making an in-court identification of Henry as “looking like” the masked robber. She saw similarities in the eyes, nose and hair. He was lighter in complexion than the man with the gun, and Campbell was not in fear when she made her observations.
The victim of a crime may be said to store a mental picture of the criminal in his mind during the exciting events, and he draws upon this image as he later tries to give investigators a description, or make an in-court identification. Some witnesses verbalize their assurances of being correct with more positiveness than others, and often, the prosecutor wishes he had a more dramatic person on the stand. Mrs. Campbell impresses us as offering an honestly arrived at conclusion of the identity of Henry, and the statements she gave to officers immediately after the crime were harmonious with her testimony. Some corroboration of this is furnished by other witnesses who made statements concerning the masked robber to officers immediately after the crime.
As to Henry Smith’s claim of error because of denial of severance, he gives us no substantial example of prejudice that he suffered thereby. This is a subject properly left to the sound discretion of the trial judge and should not be disturbed unless abuse is shown.
Denial of severance of the trial as requested by Henry Smith was within the court’s discretion, which was not abused. United States v. Berlin, 472 F.2d 13, 15 (9th Cir. 1973). It was not error to refuse to permit the expert to testify. United States v. Amaral, 488 F.2d 1148, 1153 (9th Cir. 1973); United States v. Brown, 501 F.2d 146, 150-51 (9th Cir. 1974). The proposed “theory of the case” instruction reads as follows: “Henry Albert Smith contends that the eyewitnesses to the crime had insufficient opportunity to observe the robber, and that her identification of him as *1364the robber is not correct.” It is an argument, not an instruction, and was properly refused. The instruction defining a dangerous weapon was sufficient. (R.T. VIII, p. 236, 1. 16-23) United States v. Beverley, 416 F.2d 263 (9th Cir. 1969).
AFFIRMED.