(CNN) -- The man accused of being the East Coast Rapist tried to hang himself in his jail cell Saturday, police said, one day after he was arrested thanks to DNA from a tossed cigarette butt and an anonymous tip.
Aaron Thomas, 39, was under suicide watch Saturday -- with cameras focused on his cell and a guard outside -- when he was spotted, said New Haven, Connecticut, police spokesman Joe Avery.
After the attempt, Thomas was taken to Yale New Haven Hospital "for evaluation" and is expected back in jail sometime on Saturday night.
"He's fine," Avery said.
Police said earlier Saturday that DNA evidence connects Thomas with sexual assaults on 12 women in Maryland, Virginia, Connecticut and Rhode Island between 1997 and 2009.
Earlier this week, police in Virginia got a valuable tip that helped to lead authorities to focus on Thomas, a law enforcement source familiar with the investigation said Saturday.
Investigators kept Thomas under surveillance and arrested him Friday -- having tested a cigarette butt he had discarded earlier -- while he was walking on a street near his home, according to New Haven, Connecticut, police.
Thomas had appeared in court in New Haven on Thursday on an old larceny charge, the law enforcement source said. The source said "nothing is a coincidence," given that Thomas was called to court around the same time that police had begun to focus on him as the serial rapist suspect.
New Haven Police Lieutenant Julie Johnson told reporters Saturday that Thomas is now being held on $1 million bail after being charged with sexual assault in the first degree, burglary in the first degree and risk of injury to a minor.
He also faces additional charges as a fugitive from justice in Virginia's Prince William County with charges of rape, abduction and the use of a firearm in a felony.
"DNA was collected and subsequently matched by the Connecticut state forensic sciences lab confirming that Thomas was the East Coast rapist," Johnson said.
Thomas was arrested after a long manhunt. It wasn't immediately clear if he had retained a lawyer.
Early this week, six local law enforcement agencies, the FBI and the Department of Justice launched a joint website -- using the domain EastCoastRapist.com -- to solicit information from the public about a man they called a "brazen, cold-blooded rapist." Billboards along highways publicized the police sketch of the suspect.
The EastCoastRapist.com website said "Captured" on Saturday without offering further detail.
At a news conference Saturday, Johnson did not take questions from reporters, saying the case remained sensitive.
First Sergeant Kim Chinn, a spokeswoman for the Prince William County police department, told CNN affiliate WJLA that collective work of a recently formed multiagency task force and "an anonymous tip in the past few days" helped spur the investigation this week.
"As soon as he was identified, things did happen quickly," Chinn said. "We are all breathing a sigh of relief."
CNN's Susan Candiotti and Dana Garrett contributed to this report