Parents of Murdered NYC Jogger are 'Broken,' Desperate for Killer's Arrest

— -- The devastated mother of a Queens woman who was murdered while jogging nearly one month ago is "broken," she told ABC News today, but confident her daughter's killer will be caught.

On Aug. 2, 30-year-old Karina Vetrano was strangled to death while jogging alone on a path where she and her father often ran together in Howard Beach, New York.

Nearly one month after her death, about 85 tips have come in, but the case remains unsolved.

The New York Police Department (NYPD) still has no matches to DNA recovered from the scene. Chief of Detectives Robert Boyce said Tuesday the killing is still believed to be a random attack.

"It hasn't been a roller coaster -- it's been one big downhill slide," Karina's father Phil Vetrano told ABC News. "There are no ups in this. And it's getting worse and worse. So we need to find this predator."

Police have talked to known shoplifters and panhandlers in the area and have traced possible escape routes. Because surveillance cameras did not capture a suspect, police said they are relying on witness recollection and have been interviewing joggers and bicycle riders every day.

Earlier today, police released a sketch of a specific witness they would like to identify and interview.

"Right now, I am a broken, broken woman," Karina's mother Cathy Vetrano told ABC News. "But I want to say this: I am 100 percent confident that this person will be caught."

She pleaded with anyone who may be helping the killer evade police to come forward.

"That person, if you're harboring him -- if you're trying to protect him -- he could do it to you. He could do it to your loved one. Because he killed my daughter, not in self defense, not because he had a fight with her, because he just killed an innocent, young, petite woman," she said.

"I beg of you to do what you know is right," she said. "Be courageous and make the phone call."

Watch the interview Thursday morning on "Good Morning America."