INDIANAPOLIS (WISH) — Sherese Walker-Bingham was murdered at White River State Park 12 years ago this week. Her family is still convinced they know who did it.

Indiana State Police are keeping their options open while asking the public for help.

“At first it was anger for me. Lot of anger. Over the years I got rid of the anger and turned it over to God,” Sherese’s brother Keith Walker said.

Walkers anger was focused mainly on one person: Sherese’s husband Eugene Bingham Jr.

At the time of her death, Sherese had discovered he had been having a long term affair, which Walker believes could have been his motive.

“He knew where she walked the dogs at. He knew what time she was going to be when she left the house,” Walker said.

In 2014, Eugene Bingham Jr. was arrested and charged with her murder.

“He flunked two lie detector tests,” Walker said. Lie detector results are not admissible in court.

Eventually, the charges were dropped.

“We try not to get focused on one theory or idea. We certainly have different theories of what happened that day, but we’re also opened minded to other information that could help us,” Indiana State Police Sgt. John Perrine said.

Sherese had been walking her two highly trained guard dogs when she was killed. ISP still believes those dogs provide a crucial clue.

“I think the dogs tell us that it was possible that it was somebody that was known to her, because the medics couldn’t even get to her. The dogs were so protective, but we can’t stand on just that information. We have to find more facts, more information, more evidence,” Perrine said.

Walker has a plea to anyone that has the information that could put his sister’s killer behind bars. “If you know something, say something. You’ve been holding on to this all these years and I know you have a guilty heart. Just let it go,” Walker said.

Indiana State Police says anyone with information can come forward anonymously with a tip. That person could receive a reward.