Aaron Thomas, right, arrives in police custody at an airport in Manassas on Nov. 29, 2011. Escorting Thomas is Detective Steve Piaskowski. (Tracy A. Woodward/The Washington Post)

Aaron Thomas, suspected of raping women up and down the East Coast over the past two decades, is scheduled to enter guilty pleas in two Northern Virginia counties, probably sparing several victims from enduring grueling trials, law enforcement officials said.

The pleas, slated for Tuesday in Prince William County and Nov. 30 in Loudoun County, are in two separate cases that police linked to Thomas through DNA evidence. The cases were among at least a dozen confirmed attacks in Virginia, Maryland, Connecticut and Rhode Island that police attributed to the East Coast Rapist, dating to the mid-1990s.

Although Thomas could withdraw the pleas until a judge accepts them in court, the hearings indicate that he has agreed to take responsibility in the attack of three teenage trick-or-treaters in Prince William on Halloween in 2009 and rape of a 41-year-old woman in a Leesburg apartment in May 2001. In both cases, Thomas and the victims did not know each other, and he allegedly approached them from behind and told them that he had a weapon before raping them.

Prince William County Commonwealth’s Attorney Paul B. Ebert said Wednesday that Thomas has agreed to plead guilty to two charges of rape and three charges of abduction in the Halloween case — all counts that carry maximum sentences of life in prison. Prosecutors are dropping additional firearms charges. As part of a plea agreement, defense lawyers and prosecutors will argue over sentencing at a later hearing.

Thomas’s attorney declined to comment.

Ebert said the pleas will spare victims from having to go through a trial, which had been scheduled for January, and will put Thomas before a judge for sentencing instead of a jury. Ebert said that if Circuit Court Judge Mary Grace O’Brien accepts the pleas, victims would be allowed to testify at a sentencing hearing, and Thomas also would have an opportunity to address the court. At a hearing this year, Thomas asked to speak in court but was not given the chance.

“The evidence in this case is very overwhelming,” Ebert said, adding that the court will be made aware of the total history of the case. “He should be sentenced harshly.”

Should Thomas enter the guilty pleas and receive long sentences, it is unlikely that prosecutors in Prince George’s County, Fairfax County and New Haven, Conn., would pursue rape cases against him. Authorities said there is some discussion about a “global sentencing” that would in effect put an end to any further prosecutions in the case.

Police have testified that Thomas admitted his role in numerous attacks almost immediately after his arrest in New Haven in March 2011. Police had linked Thomas to the rapes after a long manhunt that accelerated after the Halloween 2009 attacks. Detectives had Thomas on a short list of suspects shortly before his arrest, and a Crime Solvers anonymous tip sent him to the top of the list.

Detectives following Thomas ultimately scooped up a discarded cigarette and matched his DNA to the cases. He was originally held in Connecticut but was moved to Virginia in late 2011 to face the Prince William charges, which arise from the most recent attack. In that case, Thomas allegedly approached three teenagers in the dark rain, said he had a gun, led them into a wooded ravine and raped two of them as they feared for their lives.

Thomas, 41, was an out-of-work trucker who grew up in the Washington region and moved to New Haven several years ago. The attacks police linked to him were near areas where Thomas was living or working and were in areas with which he was familiar, police said. Some of the attacks happened outdoors, with the victims accosted on public streets and directed into wooded or secluded areas; some attacks were in victims’ homes. Victims reported that their attacker used a gun, a knife, a screwdriver and even a broken bottle to subdue them.

Lawyers appointed to represent Thomas had been preparing a defense that might have included a claim of insanity. Such an argument would have had Thomas acknowledging his involvement in the crimes but also claiming that he either didn’t know right from wrong at the time or had irresistible impulses. His attorneys notified the Prince William County Circuit Court in recent days that they were abandoning that approach and would not offer evidence of insanity or expert testimony about Thomas’s mental health.

At a preliminary hearing in March in the Prince William case, Thomas kept his head on the table as the three victims described the attack. One of the girls, who was not sexually assaulted, testified that she was able to surreptitiously text and call her family, friends and ultimately police, who narrowly missed the attacker as he fled through the woods.