Attorneys made their opening statements Wednesday in the trial of a Manorville man accused of murdering two women in the early 1990s. 

Prosecutor Robert Biancavilla told the jury that 50-year-old John Bittrolff Jr. viciously murdered two prostitutes, who were both found nude and strangled with their skulls crushed. 

Rita Tangredi was found in November 1993 in East Patchogue, and Colleen McNamee was found in January 1994 in Shirley. Both discoveries were made in wooded areas. 

The prosecutor explained to the jury how DNA evidence from Bittrolff's brother, who had been arrested in 2013 in an unrelated case, led detectives to him. His brother's DNA had been entered into a state DNA database and showed a family connection to the DNA recovered from both murder scenes. 

"We have very sound proof that he is the killer," said Biancavilla. 

During his opening arguments, defense attorney William Keahon told the jury that the presence of his client's DNA does not mean that he is their killer.

John Bittrollf's trial will continue Thursday and is expected to last several weeks.