People v. Soto

[Editor’s Note: This brief is based on three excerpts from pages 198, 201, and 207 of the casebook to provide comprehensive details.] Frank Soto (defendant) was charged by the State of California (plaintiff) with forcible rape of a 78-year-old woman and using a knife in the commission of the crime. The victim could not identify the rapist because the assailant wore a mask. Police seized a bedspread from the victim’s bedroom that had semen present. A blood sample was taken from Soto for DNA comparison to the semen. At trial, a criminologist, Robert Keister, testified that the DNA matched with a probability of 1 in 189 million of finding the same DNA pattern at random in Orange County’s Hispanic database (Soto was Hispanic). Keister tested the DNA by comparing four autorads showing DNA fragments at different points. Any nonmatch would indicate that the fragments were not from the same source, but all of the fragments matched. From the DNA sample, Keister compared the four fragments with Orange County’s DNA database, determined the odds of finding each pattern randomly within the Hispanic database, and multiplied the four products (for instance, a 1-in-1,000 chance of a random match for one autorad multiplied by a 1-in-100 chance for the random match for a second autorad, yielding a chance of a random match for both of 1 in 100,000). At trial, Soto was acquitted of both the forcible rape and knife-use charges but was convicted of attempted rape, which was a lesser included offense. Soto appealed his conviction, arguing that the trial court erred in allowing Keister to testify about the 1-in-189-million DNA-profile match. Soto argued that the means of applying a match rate were outside general acceptance in the relevant scientific community, which was the Kelly standard, California’s variation on the Frye test.