Detectives at the Phoenix Police Department took the nurse, Nathan Sutherland, 36, in for questioning in the case on Tuesday, police said, and collected a DNA sample from him that matched that of the child, a boy who was born Dec. 29. Sutherland was being booked on Wednesday morning at the Maricopa County Jail on one charge of sexual assault and one charge of vulnerable adult abuse, police said.

“Through a combination of good-old police work, combing through evidence, talking to people and following up on information, combined with the marvels of DNA technology, we were able to identify and develop probable cause to arrest a suspect,” Jeri L. Williams, the Police Department’s chief, said at a news conference on Wednesday.

Detectives started to focus on Sutherland because he was among the medical staff members at the nursing home, Hacienda HealthCare, who were assigned to care for the woman around the time last year that police believe she was assaulted. The woman had been at the nursing home since 1992 and since then had been in the same condition, unable to communicate or move, according to medical records. A lawyer for the family did not immediately respond to a request for comment on Wednesday.

Sutherland, a licensed practical nurse, had worked at Hacienda since 2011 and was still working there as of Tuesday, police said. A spokesman for Hacienda did not immediately respond to a request for comment Wednesday.

Sgt. Tommy Thompson, a Phoenix police spokesman, suggested that Sutherland had not been cooperating with detectives. Thompson noted that Sutherland offered a DNA sample only after he was shown a court order to do so and that he invoked his Fifth Amendment right to avoid self-incrimination when he was arrested.

A 911 call made at Hacienda on Dec. 29, which the police recently released, showed that the nursing home’s staff members were unaware that the woman had been pregnant. A woman who made the call reported that the baby was in distress.

On Wednesday, Thompson said the boy was doing well.

This article originally appeared in The New York Times.