Federal prosecutors in Washington announced an indictment Tuesday against the man wanted for at least six sexual assaults that took place in D.C.-area hotels nearly two decades ago and all linked by his DNA.

But the suspect not only remains on the loose — his identity is unknown.

So for the first time, the U.S. Attorney's Office for the District of Columbia pursued the indictment for a John Doe profile based on DNA evidence.

Composite sketch created in 2003 on the left, and an age-progressed composite sketch on the right. FBI/Montgomery County Police Department

"The survivors in this case are going to live with this for the rest of their lives, and this person needs to be held accountable," Peter Newsham, the Metropolitan Police Department's chief of police, said at a news conference.

Jessie Liu, the U.S. attorney for the District of Columbia, said it was necessary to indict the suspect, even if he hasn't been identified, because the 15-year statute of limitations deadline is coming up on the case.

The FBI said two of the six known assaults took place in June 2003: One involving a 29-year-old female housekeeper at the Jefferson Hotel in northwest Washington, and the second involving a 22-year-old female housekeeper at the Marriott Courtyard Hotel in Greenbelt, Maryland.

The first known case involving the suspect occurred in May 2002, when an 18-year-old woman in northeast Washington was picked up on the street by the man and sexually assaulted while he gave her a ride, police said.

#FBI Special Agent in Charge DeSarno: “If you recognize this person, if this box cutter or ring are familiar, if you have seen these items before, we need you to call law enforcement and provide the information. The public’s assistance is vital in solving this case.“ pic.twitter.com/KlihcXsn8u — FBI Washington Field (@FBIWFO) June 19, 2018

In another case in May 2003, a 68-year-old female housekeeper at the Jefferson Hotel was bound with a necktie and raped.

The FBI said the suspect may also be involved in at least eight other incidents, including three reports of sexual assault, at various hotels in the Washington-Virginia-Maryland metropolitan area from August 1998 to February 2006.

Hotel housekeepers were involved in nearly all of the cases. Police said the assailant entered hotel rooms as they were being cleaned, and he used either a box cutter, necktie or cord to threaten his victims.

The indictment allows the unknown suspect to be prosecuted at a future date — even after the statutes of limitations have passed in the majority of these cases.

Witnesses described the suspect as a man about 5-foot-7 to 5-foot-10 tall, with a medium build and medium complexion, officials said. He would be in his 30s or 40s currently.

The suspect's ring that came off during a 2003 assault at the Renaissance Hotel on 9th Street in NW Washington, D.C. FBI

Among the evidence found at one of the crime scenes was a ring that was taken off the rapist during an assault, and a box cutter with the name Debbie handwritten on it, the FBI said.

A reward of up to $45,000 is being offered by law enforcement. Anyone with information can submit a tip to the FBI at tips.fbi.gov.

DNA has proven integral in solving other high-profile serial crimes, most recently the capture in April of Joseph DeAngelo, 72, who police say was the unknown assailant in at least a dozen murders, 45 rapes and 120 home burglaries during the 1970s and 80s in California.

While DeAngelo faces murder charges, the rape accusations against him are older than California's statute of limitations, which don't apply retroactively despite recent changes in the state's laws.