New York City police have recovered a useful DNA sample from the body of slain Howard Beach jogger Karina Vetrano but have so far been unable to find a match with any known person, according to a law enforcement source.

Detectives working on the case also have investigated about two dozen leads but none have proved significant, the source said.

During a standing-room-only forum at St. Helen Roman Catholic Church, Queens Borough president Melinda Katz said she has pushed through an allocation of funds to provide more surveillance cameras to watch everyone entering Spring Creek Park, where Vetrano died.

“If you enter the park, if you leave the park you will be photographed,” Katz said.

Some residents were agitated over the way tall weeds obscure visibility into the park and a representative of the National Park Service said the agency estimated it would cost $500,000 to clear out weeds on a one-time basis, but that it was difficult to eradicate.

Officials said they have interviewed known sex offenders in the area.

St. Helen, at 157-10 83rd St., is about a mile from where Vetrano’s body was discovered last week in the reeds near 161st Avenue and 78th Street. Her funeral was held there Saturday.

Vetrano, 30, a St. John’s University graduate, was found dead Tuesday after she went for a routine jog about 5 p.m. When she didn’t return home, her father, Phillip Vetrano, called a neighbor in the NYPD, and police and residents began a search that ended with her body being discovered about 9 p.m.

An autopsy determined Vetrano had been strangled. Police said she was sexually assaulted, her clothing was in disarray, and that she apparently had fought for her life.

Since the killing, police and crime-scene experts have been scouring the area for clues. On Sunday, detectives visited homes in Howard Beach to locate additional home surveillance videos they are tediously compiling to determine Vetrano’s final route and discover any useful leads, residents said.