Houston police issued an arrest warrant Wednesday for a man suspected of fatally shooting a doctor of former president George H.W. Bush.

Mark Hausknecht was shot on the morning of July 20 while he biked to work, police said.

Police said they searched the home of Joseph James Pappas, the suspect, and are looking for him.

Police said Pappas, described as a fit 62-year-old white man, has for more than 20 years held a grudge against Hausknecht after his mother died during a surgery.

“This man is dangerous, this man is capable, this man has some skills,” Houston Police Chief Art Acevedo said at a news conference, noting that the suspect probably has multiple firearms and that he had not been seen for nearly two days. Pappas sent a suicidal text to an associate on Tuesday night, prompting officers to check his home, Acevedo said.

Police said surveillance footage captured from a Metro Lift bus shows a suspect in the July 20 killing of cardiologist Mark Hausknecht. (Houston Police Dept.)

The chief declined to elaborate on the evidence the department has connecting Pappas to the killing.

The shooting occurred on a hot Friday morning after the gunman followed Hausknecht by bike to work at Houston Methodist Hospital, The Washington Post reported. The gunman shot the cardiologist, dressed in blue scrubs, twice in his torso, less than one mile from the hospital.

“There was a lot of planning that went into this,” Acevedo said. “There was a lot of planning and sadly some skill.”

Hausknecht, who graduated from Baylor College of Medicine and attended Johns Hopkins Hospital for residency, was an internationally respected cardiologist, according to a Washington Post report. Hausknecht in 2000 treated Bush for heart problems, according to the Associated Press.

“Mark was a fantastic cardiologist and a good man,” Bush said in a July statement. “I will always be grateful for his exceptional, compassionate care. His family is in our prayers.”

Georgia R. Hsieh, Hausknecht’s wife, in a statement described the killing as “senseless,” asserting that guns do not make America safer.

“Now my family and I have joined the ranks of the tens of thousands of other grieving Americans who lose innocent loved ones each year,” she said the day after he died.

“While law enforcement has given you their focus on finding the criminal, I am asking you to use your vote and your voice to stem the tide of this growing public health epidemic.”

Read more: