A man suspected of killing Dr. Mark Hausknecht may be on the run and suicidal, according to Houston police. Sixty-two-year-old Joseph James Pappas was last seen Tuesday, when Houston police received a tip that he might be involved.

Dr. Mark Hausknecht was a friend, surgeon, and former cardiologist for President George H.W. Bush. His death made headlines two weeks ago when he was found dead near a construction site in Houston. Hauskenecht was reportedly riding a bike to his place of work, Houston Methodist Hospital, when he was shot three times by an unknown assailant.

Investigators now believe that Joseph Pappas is the man who killed him, a man who is also an avid bicyclist. Police received a tip on Tuesday, July 31, that Pappas may have been involved. After searching his home early Wednesday morning, police couldn’t locate Pappas, but did discovered undisclosed evidence they say links him to the crime.

Authorities have also put together a potential motive in the shooting. Pappas’s mother died while in surgery under Dr. Mark Hauskenecht’s care over twenty years ago. Investigators believe Pappas may have planned the killing as revenge for his mother’s death.

Pappas is considered armed and dangerous and potentially suicidal, after police found a text message from him on Tuesday that said he planned on killing himself.