RIVERHEAD, N.Y. – As lab technicians analyzed a DNA sample from a New York man following a small-time criminal conviction, they discovered the sort of tantalizing clue officials hoped for when New York became the first state to begin collecting DNA from every person convicted of any crime.
The sample wasn't a match with DNA found at any known crime scene. But it was close. Someone related to the donor had left DNA on the bodies of two prostitutes slain in the 1990s.
That nugget of information gave investigators the opening they needed to follow a trail of other genetic clues, in trash bags, coffee cups and cigarette butts, that ultimately led them to the donor's brother, John Bittrolff.
The 50-year-old carpenter is currently on trial in a Long Island courtroom, charged with murdering the women in 1993 and 1994. He says he is innocent.
"This was inadvertent," Suffolk County prosecutor Robert Biancavilla said of the initial partial DNA match that led to the arrest. "The fish just happened to jump in the boat."
New York's Division of Criminal Justice Services says the clue was one of more than 1,450 investigative leads that have been developed as a result of the state's decision in 2012 to collect DNA samples from all criminal convicts, no matter how minor their offenses.
New York first began collecting DNA in 1996, at first just from people convicted of homicide and some sex offenses. But since the "all crimes" database was created in 2012, the number offender genetic profiles in its files has risen from 453,520 to 618,712 in 2016.
Eight state labs now create the profiles and compare genetic material to try and solve crimes.
The expanded sampling "clearly has been a success," said Richard Aborn, head of the Citizens Crime Commission in New York City. "It's another example of how technology and science can be a crime-fighting tool."
The trail that police said led to Bittrolff began with a sample submitted by his brother, Timothy Bittrolff, following his misdemeanor conviction for violating an order of protection in 2013.
After the analysis of the sample indicated it was a partial match to DNA left on the two victims slain in 1993 and 1994, investigators looked at Timothy Bittrolff's brothers.
First, they retrieved a cigarette butt that one brother, Kevin Bittrolff, had tossed from his car. But his DNA wasn't a match.
Investigators then set up a camera outside John Bittrolff's home in Manorville. When he left nine bags of trash outside, they swooped in.
DNA was retrieved from a plastic cup in the trash, and found to be a match with the material found on the slain women. Bittrolff was arrested and when he sipped from a coffee cup during questioning, authorities got another sample of his DNA. That sample also matched the crime scene evidence.
"The killer left his calling card," Biancavilla told jurors this week.
William Keahon, Bittrolff's attorney, contends that DNA alone will not be enough to convict his client.
"Why does he have to be the killer?" Keahon asked jurors Wednesday at the opening of the trial in a Suffolk County courtroom. "Sexual relations don't equal a killer."
He conceded that Bittrolff said "no" when detectives asked him if he had ever had sex with a prostitute. But, he added, "I don't know a guy that would say, 'Yeah,' in a police station when it's a crime to be with a prostitute. And you're married. And you have two sons."
The nude bodies of Rita Tangredi, 31, and Colleen McNamee, 20, were found nine miles apart in late 1993 and early 1994, respectively. Both women had been strangled and suffered severe head injuries. Investigators found wood shavings on both bodies, authorities said.
A New York state panel is considering whether to allow a forensic method used in 10 other states called familial DNA analysis that could lead to similar breaks in cold cases. It allows investigators to expand the parameters of its DNA search to try to find people who may be related to the one who committed the crime.
Familial DNA testing was not used in the Bittrolff case, prosecutors said.
Anthony Tangredi was 11 when his mother was found beaten and strangled to death.
"I was just overwhelmed," Tangredi, now 34, said when he heard police had arrested Bittrolff.
"I gave up hope a long time ago," he said on the eve of the trial. "I just never imagined that they would ever find a killer. It was such a cold case."
Hays reported from New York City. Associated Press researcher Rhonda Shafner contributed to this report.