The Prince George’s County police department has prohibited officers from working off-duty security jobs at house parties after a Sunday incident in which officers at a party in Upper Marlboro did not discover a drowned man’s body for more than two hours.

The officers told firefighters called to the scene in the 4200 block of Crain Highway about 1:30 a.m. that nothing was wrong, sending them away as Kevin Sehinde Akinfeleye, 22, of Lanham apparently lay dead at the bottom of a pool, authorities said.

He was not discovered until after the party had largely wrapped up about 3:30 a.m., authorities said.

Late Monday night, Deputy Chief Kevin Davis issued a directive saying county officers were no longer allowed to work off-duty security jobs at house parties. At a news conference Tuesday, Davis said it was a response to the drowning, adding that the presence of officers at such parties could give the impression that police sanction the drinking, noise and fights that can come with them.

“We realized as far as house parties, our presence does more harm than good,” Davis said.

County police will issue a comprehensive overhaul of their off-duty employment guidelines next month, Davis said. That overhaul has been in the works since December, when police appointed a major to review the practice.

Also Tuesday, Davis outlined a detailed account of the events surrounding Akinfeleye’s death.

Based on a friend’s account, investigators believe that Akinfeleye jumped in the pool with another friend about 1 a.m. Sunday, Davis said. The friend told investigators that he lost track of Akinfeleye, who had been drinking and seemed to have trouble swimming.

The friend apparently talked to a security guard at the party, then called 911 at 1:37 a.m. to report a possible drowning, Davis said. Davis said investigators believe that Akinfeleye had probably drowned soon after jumping into the pool.

Firefighters arrived at 1:53 a.m. and checked the pool with off-duty police officers working security at the party, Davis said. He said they looked at the pool — which was murky and had about 30 people in it — but did not see anything amiss.

Mark Brady, a Prince George’s County Fire/EMS Department spokesman, said those officers told firefighters that nothing was wrong, and the 911 caller did not approach them. Because of that — and because the water was too murky to see much beneath the surface — they left after looking at the pool, he said.

Just before 3:30 a.m., as the party was winding down, an officer spotted Akinfeleye at the bottom of the pool’s approximately nine-foot deep end and called firefighters again, Davis said.

Brady said they arrived to find someone performing CPR on Akinfeleye, who was pronounced dead a short time later at a hospital.

Davis said internal-affairs investigators are looking into whether anyone ordered the pool emptied after the first 911 call. He said that five off-duty Prince George’s officers were working security at the party and that authorities “probably should have found” a drowning victim after the first call.

“Very unfortunately, they didn’t see the drowning victim at the bottom of the pool,” he said.

Fire officials’ initial review of the incident revealed no wrongdoing on the part of emergency responders, Brady said.

Kemi Akinfeleye, 30, Kevin Akinfeleye’s sister, said she questions why her brother, who was scheduled to graduate from Michigan State University next year with a degree in marine engineering, would have jumped into the pool, because he could not swim.

Davis said police are investigating who hosted the party at the house, known as Broadwater Mansion. He said that promoters apparently sold tickets and that hundreds of people showed up to drink and party into the early hours of Sunday.