DEDHAM — It was getting late on the night of June 5 when Alonzo Polk called his mother to let her know where he was.
Polk, 17, had graduated from Dedham High School earlier that day, and he spent the evening visiting a few parties to celebrate with his classmates, relatives said Sunday.
Polk’s brother, Roshawn Drane, said he was also on the call with his mother and brother.
“He was checking in with her, you know, ‘Hey mom, I’m having fun,’ ” Drane said Sunday in front of the family’s home on Mount Vernon Street. “We were all talking, you know, on a conference call. And then, soon thereafter, we get the devastating call.”
Polk had gone to a party at 36 Netta Road, less than half a mile from his family’s home. Around 12:30 a.m. June 6, police responded to 911 calls reporting a possible drowning at the home. The victim, later identified as Polk, was taken by ambulance to a Boston hospital, where he died Friday morning.
On Sunday, hundreds gathered in front of Polk’s home, where a “Dedham High 2021 Senior” sign stood proudly in the front yard, and marched with his family down Mount Vernon Road and on to Netta.
Amid chants of “Justice for Alonzo!” and “AP Strong,” the group was guided along the route by Dedham police, who used cruisers to block nearby streets and keep the road clear as other officers rode along on bicycles.
After turning on Netta Road, Drane turned to the crowd and, speaking into a megaphone, asked them to quiet their chants as the family walked about 100 yards to the end of the street.
“As we walk down this street, I want silence,” Drane told them. “I want you to feel my brother’s presence.”
The route ended in front of 36 Netta Road, where members of Polk’s family placed candles on a rock wall and stood in a moment of silence. A minivan was parked in the driveway, but it was unclear whether anyone was home.
The march then returned down Mount Vernon Road past Polk’s home to Barnes Memorial Park.
Authorities are still investigating the circumstances of Polk’s death, and police are seeking criminal charges against people involved.
The Norfolk district attorney’s office said Sunday that it had assigned a victim advocate to Polk’s family after he died, according to David Traub, a spokesman for District Attorney Michael Morrissey.
“Our office will now be obtaining medical records, autopsy results, and reviewing that and the Dedham Police investigative materials that led DPD to apply for criminal complaints last week,” Traub wrote in an e-mail.
Police said Thursday they had filed a criminal complaint in Dedham District Court seeking misdemeanor charges against people whom they did not identify. Police said the names of the individuals and details of the incident submitted to the court will not be shared publicly “until such time as the Court makes a determination of probable cause and conducts an arraignment.”
The charges include furnishing alcohol to persons under 21 and reckless endangerment of a child, police said.
The home at 36 Netta Road is owned by former State Police captain James Coughlin, a one-time candidate for Norfolk sheriff. Coughlin has not responded to multiple Globe inquiries seeking comment.
Drane said his family is still looking for answers about what happened before Polk was pulled out of the pool.
“That’s the trouble — no one saw him go in, but everyone saw him come out,” Drane said.
Police have said officers responded at about 12:30 a.m. on June 6 to multiple 911 calls reporting a possible drowning in an in-ground pool in the backyard of a home on Netta Road. Police said callers reported that a teenager, later identified as Polk, had become “submerged in a pool of water.” Bystanders were performing CPR on Polk when officers arrived, police said.
Authorities have not said how Polk ended up in the pool.
At graduation, Polk was among the recipients of the Anne S. Corcoran Scholarship, according to video of the ceremony held June 5. In the video, Polk is seen crossing the stage in a red cap and gown, smiling as he receives his diploma to the cheers of friends.
“He just had everyone’s best interests at heart, and he would go out of his way to make sure everyone was okay,” said Rochelle Casey, a close friend to Polk since she was in sixth grade and he was in fifth.
Besides his academic achievements, Polk was also known for his skills in basketball and football. Drane said his brother had been accepted to Bridgewater State University and was hoping to play football there while studying engineering.
Drane described his younger brother as a “breath of fresh air.”
“He had plans,” Drane said. “He wanted to see the world.”
Nick Stoico can be reached at firstname.lastname@example.org.