When the Bike Path Killer first attacked in 1981, investigators did not have the ability to tie someone to a crime through DNA evidence.
Nine years later, when the serial rapist attacked and killed Linda Yalem, it took out-of-town lab technicians months to analyze the DNA left behind.
But last weekend, scientists at an Erie County forensic lab needed just hours to link a DNA sample taken from a suspect in the murders and rapes to genetic material left on the victims.
"The forensic world is a lot different than it was 16 years ago," Amherst Police Chief John J. Moslow said in a news conference Monday after the arrest of Altemio C. Sanchez.
Collection and analysis of DNA material were key components of the search for the Bike Path Killer, police said.
That scientific evidence connected crimes, helped paint a portrait of the killer and ultimately led police to Sanchez, who is suspected in three murders and at least seven rapes.
Scientists and defense attorneys caution that DNA isn't a silver bullet on its own, but police say it's a powerful tool when combined with tried-and-true detective work.
"Old-fashioned police work brought everything together, and DNA evidence sealed the deal," Erie County District Attorney Frank J. Clark said in the same news conference.
This is not the first high-profile local case to turn on DNA evidence. Hair fibers found in a hat buried at the scene of the shooting of Dr. Barnett A. Slepian led police to his killer, James C. Kopp.
And investigators say DNA is becoming increasingly useful -- particularly in cold cases -- as it has become easier to obtain and analyze evidence.
"This is the fingerprint of the 21st century," said Erie County Sheriff Timothy B. Howard, "but it's better than a fingerprint."
Anyone who watches "CSI: Crime Scene Investigation" or other popular television crime dramas has a basic fluency in the use of DNA, or deoxyribonucleic acid, as evidence.
The double-helix-shaped strands of DNA store unique genetic information and are exactly the same in every cell in someone's body.
DNA first came into wide use in criminal investigations for identification purposes in the late 1980s, said Kenneth F. Jonmaire, retired chief forensic investigator for the Niagara County Sheriff's Department.
"DNA is highly convincing evidence," said Jonmaire, who is an instructor at Buffalo State and Hilbert colleges.
Initially, scientists had to match entire strands of DNA, a process that took at least a month.
The DNA had to come from a fairly large sample of blood, the work was labor-intensive, and few labs did such tests.
Beginning in the mid-1990s, scientists developed the ability to match DNA by looking at 13 specific spots on the strands instead of the entire strand.
"The technology has undergone quite dramatic changes since the early days," said M. Scott Goodman, an associate professor and chairman of Buffalo State's chemistry department.
This saves time, and technicians can extract DNA from a wider array of materials, including saliva, semen, skin cells, hair, urine and sweat.
The contrast between DNA collection and analysis in the early 1990s and today, Jonmaire said, is "the difference between an abacus and a computer."
DNA is the evidence that connected all of the Bike Path Killer cases -- even crimes that police initially weren't sure were the work of the same attacker.
In the earliest rapes, DNA wasn't available, and police are able to link the assaults to the Bike Path Killer only through victims' descriptions and the attacker's methods.
Police at first believed that the 1990 killing of Yalem in Amherst was the only murder the serial rapist committed.
But in 2004, investigators used DNA to link the 1992 slaying of Majane Mazur in Buffalo to the other attacks.
And police didn't connect the September 2006 murder of Joan Diver to the attacks until DNA found in the Clarence woman's sport utility vehicle matched DNA taken from the other victims.
Investigators had not previously revealed where the DNA evidence was found, but Howard this week confirmed that it was found on the steering mechanism of the SUV. He wouldn't say what the DNA evidence was.
DNA also helped create a profile of the Bike Path Killer.
In 2004, DNA analysis performed by a Florida company indicated that the attacker is likely of a mixed ethnic background that includes European and Native American heritage.
DNA even told investigators that between the 1992 and 1994 attacks, he lost the ability to produce sperm.
After investigative work prompted police to focus their attention on Sanchez, undercover officers acquired a DNA sample from drinking glasses he used in an Amherst restaurant.
Erie County's Central Police Services forensic laboratory was able to get a match between Sanchez's DNA and the Bike Path Killer's DNA within hours Saturday.
In the Kopp case, police turned their sights on Kopp after finding strands of hair in a baseball cap buried near the East Amherst scene of the Slepian slaying.
Investigators later matched the DNA taken from that hair sample to DNA from a toothbrush Kopp left behind at a house where he had stayed briefly, according to court documents.
The state maintains two DNA databases. Its database of DNA collected from offenders has 225,000 samples, and a database of DNA obtained from crime scenes has 19,000 samples.
Even DNA advocates note that because humans are involved in the collection, storage and analysis of the samples, DNA matching isn't 100 percent accurate.
However, DNA can be "the glue that binds" a case, said Howard, the Erie County sheriff, and he thinks the law should require samples from anyone convicted of a misdemeanor.
But critics say that taking DNA samples from anyone convicted of a crime violates the Fourth Amendment requirement that probable cause exist for a search or seizure.
DNA samples should only be taken on a case-by-case basis where police have proved to a judge the need for a particular person's DNA, said Timothy W. Hoover, an assistant federal public defender in Buffalo.
However the legal battle plays out, the investigative value of DNA is only going to grow, Jonmaire said.
"We want ultimately to be able to do [the analysis] at the crime scene," he said, "and do it in half an hour."