PRINCETON, Mass. — DNA evidence and an attentive state trooper helped find the man authorities believe killed a New York City woman who was out jogging near her mother’s Massachusetts home last summer, authorities said Saturday.

“Good afternoon. We got him,” Worcester County District Attorney Joseph Early Jr. proclaimed at a news conference outside the police station in Princeton, a small community of about 3,500 residents in central Massachusetts.

“We’re very comfortable that we’ve got Vanessa Marcotte’s killer,” Early said.

The body of 27-year-old Marcotte was found Aug. 7 in some woods about a half-mile from her mother’s house, where the young woman was visiting family. Marcotte, who worked as an account manager for Google in New York, had gone out to run several hours earlier.

Police said throughout the investigation they believed Marcotte fought her attacker and the suspect had scratches on his face, neck and arms. On Saturday, Early said DNA taken from Marcotte’s hands during an autopsy helped solve the case. The DNA was used to help create a profile of a suspect, which was released two months ago. It also matched the DNA of 31-year-old Angelo Colon-Ortiz, who lives in nearby Worcester and who police believe was working in the area at the time of Marcotte’s attack.

“It’s through her determined fight and her efforts that we obtained the DNA of her killer,” Early said.

Colon-Ortiz was charged Friday with aggravated assault, aggravated assault and battery and assault with intent to rape. Early said more charges are expected.

The district attorney credited “an alert state trooper assigned to the detective unit” with recently spotting a dark SUV, the type of vehicle witnesses reported seeing in the area. He said that trooper also noticed the driver matched the profile released in February, which determined the suspect in Marcotte’s killing was a Hispanic or Latino man, about 30 years old, with light- to medium-toned skin, an athletic build and either balding or with short hair.

Unable to find a piece of paper, Early said the trooper wrote the vehicle’s license plate number on his hand. He looked it up, visited Colon-Ortiz at home and obtained a voluntary DNA sample that proved to be a match.