HOPKINTON, Mass. — The death of a teen whose body was found near her family’s Hopkinton home last month has been ruled a suicide, authorities said Tuesday.

The state’s medical examiner found that 16-year-old Mikayla Miller, who is Black, died by suicide, according to a statement from the Middlesex District Attorney’s office. But the office said the case is still under investigation.

“Our investigation into the events surrounding Mikayla’s death remains active and ongoing,” the office wrote. “We will continue to explore every investigative angle necessary as we do that work and intend to issue a complete and thorough report at the conclusion of the investigation.”

The handling of the case has drawn scrutiny from activists and from Miller’s mother, Calvina Strothers, who previously said police hastily called it a suicide and failed to complete a thorough investigation.

Miller’s body was found April 18 in a wooded area about a mile from her home. A health app on her phone tracked movement from 9 to 10 p.m. the night before, according to the district attorney’s office. It showed that she walked about 1,300 steps, which matches the distance between her home and the area where she was found.

But her mother has raised questions about an alleged attack on her daughter. She said Mikayla was attacked by five white teens in Hopkinton the day before her body was found. Activists have suggested that the death could be a hate crime. Miller was Black and a member of the LGBT community.

Strothers could not immediately be reached for comment Tuesday.

According to an account from the district attorney, Miller was involved in an altercation with two teens in a residential building in Hopkinton the evening before her body was found. Two other teens were also in the room, and another was in a car outside. After the fight, police were called to Miller’s home and found she had been punched in the face.

Officers went to the homes of the two others involved in the fight and took statements.

But investigators found that all five teens involved were elsewhere later that evening, the district attorney’s office said. Cell phone data and witness accounts confirmed their whereabouts.

The district attorney previously promised to release “every shred of legally releasable information” once the investigation is complete.

The office said Tuesday that it had provided an update to a lawyer for Miller’s family.

“We will continue to be in contact with Mikayla’s family’s representatives moving forward and we are asking for continued patience as we perform this critically important work,” the office wrote.