(Image source from: ABC News)

Houston police consider that the suspect who allegedly killed the one-time doctor of former United States President George H.W. Bush held a long time grudge against the cardiologist since his mother died 20 years earlier while being operated on by the doctor.

An arrest warrant has been filed by authorities for the Joseph James Pappas, who is believed to be armed and dangerous as well as suicidal, said Houston Police Chief Art Acevedo during a press conference on Wednesday.

Officers searched Pappas home early Wednesday morning and received a tip from an individual who had information over the killing, Acevedo said.

The 65-year-old Mark Hausknecht, the cardiologist was shot on July 20 as he rode his bicycle in broad daylight in a residential neighborhood in Houston.

According to Houston police, 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.

Hausknecht was heading to work when he was shot, the president and Chief Executive Officer 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 around 30 years old, was wearing a dark jacket when he fled the incident.

Police have also released surveillance video and images from the scene, which show the gunman behind him just before the shooting.

By Sowmya Sangam