Los Angeles police detectives had been trailing a serial murder suspect for about a month during the summer of 2003 when they finally got their needed break.
Adolph Theodore Laudenberg, then 77, thought police wanted to question him as a witness in an unrelated car theft case and agreed to meet with an LAPD investigator at a Torrance doughnut shop. As they talked, Laudenberg sipped coffee out of a Styrofoam cup and occasionally paused to wipe his mouth with a napkin.
This week, the former cabdriver goes on trial in the 1972 strangulation and sexual assault of a San Pedro woman. The DNA from saliva he left behind on the discarded cup and napkin will provide the foundation for the state's case against him.
The use of "abandoned DNA" in criminal cases is a relatively new law enforcement practice, but one that legal experts said has broader implications for constitutional issues linked to privacy and protections against unreasonable searches and seizures.
UC Davis law professor Elizabeth Joh, who is following the trend, said law enforcement agencies generally have not adopted standards dealing with the collection of abandoned DNA and worries that that could pave the way for future abuse.
"We leave traces -- skin, saliva, hair and blood -- of our genetic identity nearly everywhere we go," Joh said in a 2005 Northwestern University Law Review article. "Should the police be permitted, without restriction, to target us and collect the DNA that we leave behind?"
In an interview, she said that although investigators in the Laudenberg case claimed they took DNA only for investigative reasons, "that's a constraint imposed by the police themselves, not the law."
Albert E. Scherr, a professor at the Franklin Pierce Law Center in Concord, N.H., said the abandoned DNA debate is only in its infancy, and will linger long after the Laudenberg case is concluded.
"It's old behavior for police to surreptitiously obtain a fingerprint by inviting a suspect for a cup of coffee or a cigarette," Scherr said. "But it's only recently that you can use a cup of coffee to get a sample of their DNA, which is much more powerful, much more personal and more multifaceted than the ridges in a fingerprint."
Prosecutors and police contend that a person's DNA is no different than any other clue inadvertently left behind in the public domain, whether it's a fingerprint or, in this case, saliva.
When it comes to identifying criminals, "there is no legal distinction between a genetic fingerprint and fingerprint in the traditional sense," said Deputy Dist. Atty. Lisa Kahn.
Suspects "don't have an expectation of privacy in abandoned property. And that would definitely apply to a cup left behind at a McDonald's or Denny's."
Police usually can recover DNA from suspects in several ways.
In a search warrant, police typically ask a judge for approval to seize personal objects that could contain genetic material, including toothbrushes, combs and utensils. A suspect also may voluntarily turn over a sample of his or her DNA. This can be compared to genetic material retrieved from a crime scene.
Authorities also can compare the genetic evidence from a crime scene with previously existing DNA reference samples contained in national and state forensic databases known as "cold-hit cases."
Still, case law on abandoned DNA is evolving.
Earlier this year, the Washington Supreme Court heard arguments about the legality of using DNA lifted from a self-addressed stamped envelope. In that case, authorities used the ruse of a class-action lawsuit over parking tickets to get suspect John Athan to lick and send in a selfaddressed, stamped envelope. The DNA collected from the saliva on the stamp helped to convict him of the 1982 rape and murder of a 13-year-old Seattle girl.
Among the issues before the court is whether police violated Athan's privacy when they collected his DNA.
In California, the legality of abandoned DNA has not yet come to a Supreme Court test.
However, Laudenberg's attorney, Harvey Sherman, filed Los Angeles County Superior Court briefs this month arguing that privacy issues should require judicial approval before DNA is seized from a public setting.
In the Laudenberg case, the officer who interviewed him quietly placed the napkin in his pocket, poured out the coffee and set the cup next to a trashcan. An undercover officer then retrieved the cup, according to court documents.
Police justified their actions, saying they took Laudenberg's genetic evidence from a public place where he had no expectation of privacy, according to court papers. Also, if they had obtained a search warrant, they risked tipping off the suspect to their investigation.
Superior Court Judge Anita Dymant agreed with police and ruled that authorities did nothing improper. She ruled that all DNA evidence against Laudenberg will be admissible in trial.