BOSTON (AP) — A New Jersey lawyer charged with sexually assaulting four women in Boston about 15 years ago was ordered held on $500,000 bail Monday during a hearing in which a prosecutor said authorities helped tie him to the attacks by getting DNA from a drinking glass he had used.

Matthew Nilo, of Weehawken, New Jersey, pleaded not guilty in a Boston courtroom to several charges, including three counts of aggravated rape, two counts of kidnapping, one count of assault with intent to rape and one count of indecent assault and battery. The charges stem from four attacks that happened in Boston’s Charlestown neighborhood from August 2007 through December 2008 — a time that authorities say Nilo lived in the city.

Nilo, 35, was arrested last week.

During the hearing Monday, prosecutor Lynn Feigenbaum said that in some cases, the assailant said he had a gun and threatened to kill the victim. In one case, he showed the victim a knife, she said.

The first two victims, who were both 23 years old when they were attacked, had been at bars in downtown Boston. One woman accepted a ride from a man she thought she knew and who offered to help her look for her car, but instead he drove her to Charlestown and raped her, Feigenbaum said.

The second woman got into what she thought was a taxi or livery vehicle driven by a male driver, who also took her to Charlestown and raped her, she said.

A 36-year-old woman who was panhandling was also raped by a man who offered her money if she got in the car with him, the prosecutor said.

The fourth victim, a 44-year-old woman, was attacked from behind while out for an early morning run. She fought back, poking her attacker in the eye with her gloved hand before he ran away, Feigenbaum said.

Investigators collected DNA from all four victims, including the fourth victim’s glove.

Police revisited the case last year using forensic genetic genealogy, which combines DNA analysis with publicly accessible genealogy research and historical records to narrow the pool of potential suspects, authorities said.

That identified Nilo as a person of interest. During a corporate event earlier this year, the FBI recovered utensils and drinking glasses the defendant used, authorities said. They obtained DNA from his glass that matched the DNA from the three rape victims and was a likely match to the DNA from the glove, prosecutors said.

Nilo’s attorney, Joseph Cataldo, questioned the manner in which his client’s DNA was gathered.

“I do understand that the procedures used by law enforcement are somewhat suspect,” he said outside of court Monday. “It seems that they obtained DNA evidence without ever obtaining a search warrant. If that turns out to be true, that’s an issue that will be pursued vigorously.”

If Nilo makes bail, he would have to wear a GPS tracking device, surrender his passport and stay away from the area where the attacks occurred. He is due back in court next Monday.

Nilo worked for a New-York-based cybersecurity company. He was hired in January after passing a background check and was suspended following his arrest pending further investigation, the company said in a statement.