## Facts

- A woman arrested on a minor charge was held in a detention cell at a city police station until her Monday arraignment.
- Ambrose J. Mountain, a police officer assigned as a telephone operator, repeatedly approached the detainee and suggested he could help secure her release.
- On Sunday afternoon, Mountain unlocked the cell, threatened to kill the detainee if she screamed, and forced vaginal intercourse and oral sodomy.
- After the assault, the detainee preserved semen by spitting it into a paper cup, which was taken for hospital testing.
- Lab testing indicated the semen donor had type A blood; type A is common in the general population.
- At trial, the court excluded direct evidence of Mountain’s own blood type but allowed evidence of the semen donor’s type A blood and limited testimony implying a connection; the jury was instructed that Mountain’s blood type was not in evidence.
- The defense argued misidentification and attacked the complainant’s credibility, claiming she fabricated the allegation to obtain money in a civil suit.
- The prosecution offered evidence that the complainant intended to donate any civil recovery to a rape crisis organization to rebut the claimed financial motive.
- The defense attempted to introduce a holster to show the complainant’s account was physically implausible, but the trial court excluded it for lack of foundation.

## Issues

1. Whether the court erred by admitting evidence that the semen donor had common type A blood and allowing limited references implying a relationship to the defendant after excluding direct proof of the defendant’s blood type.
2. Whether rebuttal testimony that the complainant intended to donate any civil recovery to a rape crisis organization was admissible to counter the defense claim of pecuniary motive to fabricate.
3. Whether exclusion of the defendant’s holster was error where it was offered as physical evidence challenging the complainant’s account.
4. Whether any additional evidentiary rulings warranted reversal under preservation and harmless-error principles.

## Decision

- The Court of Appeals of New York affirmed the convictions.
- The court held that admitting the semen donor’s type A blood evidence, with the limiting instruction that the defendant’s blood type was not in evidence, was not reversible error on this record.
- The court announced a prospective rule that common blood-type evidence is generally admissible when identity is disputed, subject to exclusion if unfair prejudice is shown.
- The court upheld admission of the complainant’s intended donation of any civil recovery as proper rebuttal to an asserted financial motive.
- The court upheld exclusion of the holster because the defense failed to establish that it was the holster worn at the time of the offense.
- Remaining claims were rejected largely for lack of preservation or because any error was harmless.

## Legal Principles

- When identity is contested, evidence that a defendant shares a physical characteristic with the perpetrator is not inadmissible solely because the characteristic is common; relevance remains, and exclusion turns on a showing of unfair prejudice.
- Trial courts may admit common blood-type evidence linking biological material to a potential perpetrator, while using limiting instructions and evidentiary controls to reduce risk of misuse by the jury.
- If the defense asserts that a witness is testifying falsely for financial gain, the prosecution may introduce targeted rebuttal evidence bearing directly on that alleged motive.
- Physical evidence may be excluded absent a proper foundation establishing that the item is what the proponent claims and is connected to the events at issue.
- Appellate review of evidentiary error is constrained by preservation rules and harmless-error analysis.

## Conclusion

The court affirmed the defendant’s convictions and clarified that common blood-type evidence is generally admissible on the issue of identity unless unfair prejudice is shown, while also approving rebuttal evidence addressing an alleged financial motive and enforcing foundational requirements for physical exhibits.


People v. Mountain, 486 N.E.2d 802 (N.Y. 1985)