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HOUSTON (CBSMiami) – A manhunt is underway for a Texas man who is accused of killing a cardiologist who once treated former President George H.W. Bush.

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Investigators named Joseph James Pappas, 62, as the suspect nearly two weeks after Dr. Mark Hausknecht was killed while riding his bike to work. The suspect the motive was revenge.

“The suspect’s mother was a patient of the doctor and died during surgery over 20 years ago,” said Houston police Chief Art Acevedo.

Surveillance video allegedly shows Pappas methodically following Hausknecht on his bike as he headed to work before shooting him in broad daylight.

“There was a lot of planning and sadly some skill and I’m just gonna leave it at that,” said Acevedo.

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Hausknecht, a prominent cardiologist at Houston Methodist, treated former President Bush in 2000 for an irregular heartbeat.

Pappas is a former law enforcement officer who recently tried to sell guns and ammunition online. Investigators spent Wednesday searching his home and say they found evidence that ties him to the shooting.

Neighbors were shocked by the news.

“I’m blown away that he was doing it. I mean he was a quiet man that stuck to himself,” said Richard Koenig.

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Pappas has not been seen for more than two days. Officials say he sent a text message on Tuesday to an acquaintance that he was going to kill himself.