(NEWSWEEK) — Authorities released a sketch of a man suspected of shooting and killing a doctor who had treated former President George H.W. Bush.

Cardiologist Mark Hausknecht, 65, was shot twice riding a bicycle to work in Houston on Friday at about 9 a.m. local time.

The gunman, who was also riding a bike, fled the scene, and Hausknecht was taken to hospital after flagging down an ambulance, where he died of his injuries.

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