I don't believe that Tom ever murdered anyone by his own hand.
Vito would have never allowed that because it could have implications down the road and effect Tom's stature as a lawyer.
Vito never influenced Tom to come into the family business. Vito supported Tom's decision to go to law school and when he was done it was Tom who asked Vito if he could work in the Corleone family business.
Remember what Vito told Tom about a lawyer with one briefcase?
