Three weeks after Robert Allen was killed inside his family’s Denison business, investigators have yet to identify a suspect and the reward for information leading to an arrest and conviction has climbed to $10,000.

In an emailed release, the Denison Police Department said the Grayson County District Attorney’s Office contributed $4,000 to the reward and an anonymous donor pledged an additional $5,000. The Denison Police Department previously offered a $1,000 reward.

“We absolutely want to get the person or persons responsible for this,” Lt. Mike Eppler said Monday. “We’re hoping that someone will come forward and tell us what they know and that we can bring some closure to the family.”

At approximately 10:30 p.m. on Oct. 31, Denison Police responded to a 911 call of a shooting at Allen Plumbing, which is located in the 3000 block of Eisenhower Parkway. When officers arrived at the business, they found Allen, 55, dead. Citing the ongoing investigation, Denison Police have released few details into the case, including how Allen died. But the Dallas County Medical Examiner’s Office officially ruled Allen’s death as a homicide.

Those with information regarding the case are encouraged to call the Denison Police Department at 903-465-2422.