The mystery of Michael Ewer’s death is as confounding to investigators now as it was in 2005, when the 49-year-old was found slain on a baseball field in Lansdale.

With few leads, prosecutors in Montgomery County are increasing the reward for information leading to an arrest in the homeless man’s murder to $5,000, an offer they announced Tuesday on the 15th anniversary of the tragedy.

Montgomery County District Attorney Kevin Steele said in a statement that the case remains active and has been a priority for his office and for local police.

“We want to find Michael’s murderer and bring justice to this family that has been grieving for 15 years," Steele said. "Do the right thing and share anything you know.”

Passersby found Ewer dead in a sleeping bag inside the dugout of the baseball field at Memorial Park on Oct. 20, 2005. He had been struck on the back of his head, and the county coroner ruled that the blow likely came as he was lying there asleep.

Aside from some footprints and blood splatter, there was little to help detectives at the scene. And in the intervening years, investigators estimate they have interviewed more than 100 people, some as far away as New Orleans.

“It has been an unsolved case in that community for a long time, and with the increase in the reward, we’re attempting to rekindle some interest and see what we can develop,” said Lt. James McGowan, a member of the Montgomery County Detectives' homicide unit.

The biggest obstacle facing the case is Ewer’s solitary nature. He suffered from mental health issues, detectives say, and rarely interacted with people outside the few family members he had in the area. His late sister Dorothy stayed in close contact with investigators, and made finding her brother’s killer her dying wish, McGowan said.

Anyone with information on the case is asked to call the Montgomery County Detective Bureau at 610-278-3368 or the Lansdale Police Department at 215-368-1801.