(HOUSTON) -- Houston police believe that the suspect who allegedly killed the one-time doctor of former President George H.W. Bush held a 20-year grudge against the cardiologist because his mother died while being operated on by the doctor.
Authorities have filed an arrest warrant for Joseph James Pappas, 65, who is believed to be armed and dangerous as well as suicidal, said Houston Police Chief Art Acevedo during a press conference Wednesday.
Officers searched Pappas' home early Wednesday morning and received a tip from an individual who had information about the killing, Acevedo said.
Mark Hausknecht, 65, was shot on July 20 as he rode his bicycle in broad daylight in a residential neighborhood in Houston.
The doctor was likely "targeted," when he was shot by the gunman, who was also on a bicycle when he rode past Hausknecht before turning and firing two shots at him, according to Houston police.
Hausknecht was heading to work when he was shot, the president and CEO of Houston Methodist Hospital, Marc L. Boom, wrote on the hospital's website.
"He was a brilliant physician, and he's touched a lot of lives," Acevedo said on Wednesday.
A sketch of the suspect was released a day after Hausknecht was killed. The man, who police estimate to be about 30 years old, was wearing a dark jacket when he fled the scene.
Police have also released surveillance video and images from the scene, which show the gunman behind him just before the shooting.
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