Who rides around on a bike and shoots people? Was it a case of bike-trail-rage? Shooting at people while riding a bike (especially in Texas) just sounds dumb. Did the shooter not have a driver’s license?
The usual suspects:
Love Triangle
Professional Feud
Life Insurance (spouse)
Malpractice Revenge
Outliers:
Conspiracy Theory
Random Gang Initiation Hit
Serial Killer
Since the police have no facts why jump to a conclusion