Dr. Mark Hausknecht was shot while riding his bike to work. The shooter was also riding a bike.
According to the medical examiner, the doctor was shot in the head, torso and left upper extremity.
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Authorities have released a sketch and several surveillance photos of the suspect who is seen following the doctor.
SEE ALSO: Mark Hausknecht seen in new surveillance photos with suspect who shot and killed him
New surveillance video shows moments before Houston doctor was killed
A former FBI agent says the doctor may have been targeted.
Police still do not have a motive. They are asking anyone who has more surveillance videos or photos to call them.
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On Saturday, a memorial service will be held for the doctor at the First Presbyterian Church on Main Street at 10 a.m.
Dr. Hausknecht's family says all are welcome to pay their respects.
In lieu of flowers, his family is asking for donations to be made to one of his favorite charities.
You can click here to see the list of charities he supported.