BANGOR, Maine — Nine family members of William Hilderbrand of Bangor, who police believed jumped from the Joshua Chamberlain Bridge last week, boarded two boats on Wednesday to search the Penobscot River for his body.

Other family members and friends went to the river’s edge to hunt for their missing loved one, and still others gathered at the Wabanaki Mental Health center on Exchange Street.

“It’s difficult,” Annette Newell, Hilderbrand’s aunt, said just after the boats disembarked. “It’s difficult not knowing — not knowing if it’s him.”

Police from both Bangor and Brewer went to the bridge just before midnight Nov. 4 after passing motorists called to report a woman on the edge of the structure near the Bangor side of the overpass.

Brewer officers were the first to arrive, and they saw someone jump into the cold, dark water and not resurface, Bangor police Sgt. Paul Edwards said Tuesday. A full-scale search was conducted for the jumper to no avail, he said.

Police believe that the person who went into the water was Hilderbrand because they found a purse on the bridge that contained his cell phone and identification, but they will not be able to verify that it was him until a body is recovered, Edwards said. Hilderbrand, 22, who lived his life as a woman, is officially considered missing, the sergeant said.

“You still have to have hope,” said Newell, who is from Pleasant Point, where Hilderbrand grew up. “You have to have hope you can hold on to.”

Hilderbrand left the Passamaquoddy reservation in Washington County several years ago, his aunt said.

“He had many obstacles to overcome because of who he was as a person,” she said. “That is why he left home. That’s why he moved to Bangor, where [his lifestyle] was more accepted.”

His relatives are determined to keep up the search until they get some closure, Newell said.

Hilderbrand graduated from Shead High School in 2006. He liked to be called “Jael,” and studied cosmetology at Mr. Bernard’s School of Hair Fashion in Bangor during 2008. He worked as an escort-exotic dancer for Cinnamon’s Sweets, according to his Facebook page.

No one has heard from Hilderbrand since Nov. 4, according to police and his family, and his last Facebook post was made at 11:31 p.m. that day.

The two boats carrying Hilderbrand’s family were launched onto the fast-moving Penobscot from Hamlin’s Marina in Hampden at around 2 p.m. Wednesday.

“They’re going all the way up to the [Joshua Chamberlain] bridge,” Newell said. “They don’t think his body made it down this far.”

The searchers could be seen going back and forth in the boats between Bangor and Brewer, looking for anything that might lead to Hilderbrand.

“It’s real high,” Newell said of the water level of the state’s largest river. “They think he might have got caught” on underwater logs or crib work, she said.

Police and fire crews spent several hours searching the river and riverbanks for the jumper on Nov. 4 and 5, and now are waiting, which is standard protocol in situations like this, Edwards said.

“It’s not like a pond or a lake,” he said. “It’s so treacherous. It’s so swift. We’re waiting for the call that someone found him.”

Members of Hilderbrand’s family are not the only ones actively searching the river area for him. More than 10 volunteers from Downeast Emergency Medicine Institute did a ground search from Bangor to Hampden on Saturday and DEMI officials plan to fly over the Penobscot River between Bangor and the ocean today, according to Richard Bowie, director of the group.

Shawn Picard, a distant cousin of Hilderbrand, called the Bangor Daily News from Lowell, Mass., on Wednesday to say those searching for him are determined to bring him home to the tribe.

“They will stay out there until they find him,” he said. “They won’t stop. We’re all family. We care about everybody that is tribal.”

Newell said the plan is to walk the river’s edge and to continue to search by boat from the Hampden marina south today.

“We’re not going to stop” until he’s found, she said. “That’s why we’re here.”