Deputies responded to Pelican Dr. in Oldsmar last night after 80-year-old Edwin Barthold was found dead outside of his home.
Investigators said he had been shot several times. His next door name 75-year-old Steven Larson was also found dead in his garage.
Investigators believe Larson shot Barthhold and then shot himself.
"That's a man who was hell bent there's no question he was going to kill this guy and he executed him and then decided at 75-years-old he had enough, went into the garage, sat down, put the gun in his mouth and that was the end of it," said Sheriff Bob Gualtieri.
Neighbors said the two men had been feuding with each other for years.
"There were words back and fourth, but nothing like this," said neighbor Daniel Waite.
Barthold's girlfriend had to be taken to the hospital after learning about the incident.