But in the end, it all came down to the fateful day in 1987 when the South King County truck painter complied with a court order to chew on a tiny piece of gauze.
Yesterday, King County sheriff's investigators arrested Ridgway, announcing that new DNA-testing technology had turned the 14-year-old saliva on that gauze into their golden evidence, tying him to the slayings of four women in the nation's largest unsolved serial killing.
"This has got to be one of the most exciting days of my entire career," said King County Sheriff Dave Reichert, who was one of the original detectives on the case that began in 1982. "This is not only an exciting day for the people who worked the case, but I know the community has got to be as excited about this as we are."
Ridgway was arrested about 3 p.m. yesterday as he left his job at Kenworth Truck in Renton, where he has worked as a painter for more than 30 years. He was headed to the King County Jail for booking and was expected to appear in court for a bail hearing today.
King County Prosecutor Norm Maleng was expected to file charges early next week.
Reichert yesterday was careful not to call Ridgway the Green River killer because Ridgway is not tied to the slayings of any of the other 45 women attributed to the Green River killer.
The killer is blamed for the deaths of 49 women from the summer of 1982 to March 1984. The remains of 42 have been found in either King County or the suburbs of Portland. Seven remain missing.
But the sheriff was eager to point out that three of the women allegedly connected to Ridgway through DNA evidence — Opal Mills, Marcia Chapman and Cynthia Hinds — were found in the Green River near Kent on Aug. 15, 1982, giving the elusive killer his nickname.
Ridgway is also being held in connection with the slaying of Carol Christensen, whose body was found in woods near Southeast 242nd Street and 248th Avenue Southeast in Maple Valley on May 8, 1983. Police don't have DNA evidence in her death, Reichert said, but he said they have enough other evidence that he wouldn't yet divulge.
Detectives will begin working on trying to make connections to other victims, the sheriff said, and a team of investigators has been re-formed to do that. They have loosely been calling themselves "GRTF Two," a reference to the original Green River task force that tried to catch the killer from 1984 to 1990.
"I cannot say with certainty that Gary Ridgway is responsible for all of the deaths," Reichert said, "but boy, have we made one giant step forward."
The sheriff said it's possible that some of the women whose deaths have been attributed to the Green River killer could have been victims of copycats.
Investigators also know that Ridgway has ties to Oregon, so detectives think they might be able to link him to the Green River victims whose remains were found in the Portland area, Reichert said.
He also said that anyone who recognizes Ridgway and has any information about him should call the Sheriff's Office.
Ridgway's court-appointed lawyer, Todd Gruenhagen of Seattle, complained yesterday that police hadn't let him talk to Ridgway and wouldn't even tell him where he was being held. Gruenhagen declined to speak specifically about the case but cautioned the public not to assume Ridgway is guilty just because Reichert says he is.
Ridgway lives in Auburn with his wife, Judith, down a two-lane dead-end lane marked with a "Private Road" sign. Neighbors said there are about four other houses down the road. Last night the road was cordoned off.
One of Ridgways' previous homes, in Kent, also was cordoned off, and several detectives were searching the garage.
Reichert said they have carefully preserved the gauze that Ridgway chewed in 1987 when investigators searched another previous home in what is now SeaTac. They had been waiting for DNA technology to improve enough to test the sample, hoping it wouldn't degrade too far to test. They finally submitted the samples to the state crime lab several months ago.
"We felt we had pretty much one shot at this," Reichert said.
Last month, King County Detective Tom Jensen, the last full-time Green River detective, walked into Reichert's office with four pieces of paper. Three were DNA results from semen samples from victims Mills, Chapman and Hinds. Then Jensen flipped the fourth page, with Ridgway's saliva test results, and said, "And this is the Green River Killer's DNA."
"And guess what?" Reichert said yesterday, smiling. "The charts were all the same. And we were pretty damn excited, to tell you the truth."
More satisfying to longtime Green River investigators is that Ridgway has been among the top Green River suspects all along. Another was a cabdriver who frequented the so-called Sea-Tac strip, formerly Pacific Highway South and now International Boulevard, frequented by many of the victims, many of whom were prostitutes. One suspect was a fur trapper who lived in Riverton.
But as they eliminated those men as suspects, Ridgway started becoming many detectives' No. 1 suspect.
He drove a truck similar to one described by several people. He'd been questioned by police for choking and hitting one woman, Keli McGinnis, who later would become a Green River victim.
Most suspiciously, one day the boyfriend or pimp of one victim, Marie Malvar, saw her get into a truck, said a source familiar with the case. The boyfriend followed it but lost it at a traffic light. The next day the boyfriend and Malvar's father searched the streets for the truck. They found what they believed to be the truck parked outside Ridgway's home.
Des Moines police were told the woman wasn't there. Later her driver's license was found at the airport, likely dumped there to throw off police. Malvar is still missing.
In 1984, Ridgway called the task force and told them he had information about the case, according to "The Search for the Green River Killer," by then-Seattle Times reporters Carlton Smith and Tomas Guillen. Police questioned Ridgway, but he passed a lie-detector test, Smith and Guillen say.
In 1987, investigators obtained credit-card receipts of Ridgway's purchases and found he purchased a lot of gasoline in the weeks that women disappeared, said a source close to the investigation.
But because investigators weren't able to pinpoint the exact time of death of the victims, they couldn't tie the purchases to specific dates that women disappeared, the source said.
But based on that information and other details, police got a search warrant on Ridgway's house. They didn't find any evidence tying him to the crime.
"I remember that quite a few of us felt strongly that he could be the individual that did it," said Al Matthews, a retired deputy King County prosecutor who worked on the case from 1983 to 1987.
Prosecutors believed they had enough circumstantial evidence against Ridgway to charge him and withstand any defense effort to have the charges dismissed, Matthews said. But they concluded they lacked enough evidence to bring the case to trial, where they would have had to prove charges beyond a reasonable doubt.
Prosecutors knew that if there was an acquittal, they wouldn't be able to re-try the case because of double-jeopardy rules, Matthews said "It's easy to say, 'gee whiz, why didn't you do something?' The main thing is, you get one shot."
"I am so happy," Matthews said of the arrest. "It practically brings tears to my eyes."
That was also a common reaction at the King County Sheriff's Office, where the case has consumed the careers of some of its top cops, including the sheriff.
Yesterday, Reichert took obvious pleasure in reminding reporters and the public that for years, critics assailed the Green River task force as ineffective and a waste of tax money. He recalled that one political cartoon of the time called it the "Green River Task Farce."
"This really vindicates our efforts," Reichert said. "One of the characteristics of a good investigator is you can never give up hope, because victims' families never give up hope."
Seattle Times staff reporters Peyton Whitely and Michael Ko contributed to this report.