What factors must be considered to determine the credibility of eyewitness evidence in a sexual assault case?

(1) the length of time and the conditions under which a witness was able to observe the perpetrator during the commission of the crime . . ., (2) the similarity of the description given by a witness immediately after the crime to the physical characteristics of the individual he subsequently identifies, (3) conduct on the part of the police tending to focus attention on a particular subject, and (4) presence of other witnesses at the time of the improper identification and the possible prejudicial influence of one witness' opinion on another's recollection. See Parker v. Swenson, 332 F.Supp. 1225, 1230-1231 (E.D.Mo.1971).