Portland police issued a written warning Thursday afternoon to the only homeless camper remaining in a wooded area behind the Pine Tree Shopping Center on outer Brighton Avenue.

In recent days, police have repeatedly advised about two dozen homeless people who have been camping on the privately owned land near the Westbrook line that they had to leave by Thursday or risk getting formal trespass notices. Anyone who remains at the property after receiving a written warning could be issued a court summons or arrested and charged with criminal trespass.

Three officers who visited the site Thursday afternoon found one camper, who was packing up his belongings and on his way out of the former encampment, said Assistant Police Chief Vern Malloch.

“They wrote him a trespass notice and allowed him to continue what he was doing,” Malloch said.

He said the other campsites, along with an informal network of trails, appeared to have been abandoned, but a significant amount of trash and other debris remained in what was known as Tent City or Pine Tree Camp.

“We will continue to monitor the area periodically to make sure no one returns,” Malloch said.

Police set a deadline for campers to leave after the department had an increase in service calls to the area for incidents such as domestic violence, arson and people with outstanding arrest warrants. Last week, a man living in the encampment was stabbed by another camper, police said.

City officials and advocates for the homeless urged the campers to take advantage of shelters and other services, including housing vouchers. But many of the campers said they didn’t want to stay in a crowded shelter, citing bedbugs, illnesses and other reasons.

When the shelters are full, some people sleep in chairs in the city’s General Assistance office. Portland’s tight rental market has made it difficult for people to find apartments, even if they have federal housing vouchers to cover rent.

City officials expect the debris on the site off Brighton Avenue to be removed by the property owners, which are various out-of-state corporate entities, including Brixmor Property Group, which owns the shopping center anchored by a Lowe’s home improvement store.