Three days after a mass shooting in Lake Butler, 44-year-old David Griffis died, becoming the fourth man killed in a violent outburst for which Union County authorities are still seeking a motive.

The Sheriff's Office says a former co-worker of Griffis at a Lake Butler trucking company -- 72-year-old Hubert Allen Jr. -- went on a shooting rampage Saturday morning.  He killed the company's 80-year-old founder, Marvin Pritchett, co-worker Rolando Gonzalez-Delgado, 28, and shot Griffis, a mechanic at the company for more than a decade.

A fifth shooting victim, 66-year-old Lewis Mabrey Jr., is recovering from his injures and is expected to get out of the hospital Tuesday.

After the mass shooting, Allen went to his home and committed suicide, deputies said.

Union County Sheriff's Lt. Lyn Williams said three days of interviews with people who knew have not turned up a motive for the shooting spree centered around Pritchett Trucking Inc., but his targets weren't random.

Investigators found a note at Allen's home that listed his four victims.

"Further investigation revealed by a handwritten note at Allen's house that this was a premeditated event targeting these individuals," according to a news release. "The note did not reveal a motive."

The Rev. Patrick Maxwell of Victory Christian Center said even family members do not know why Allen went on the shooting spree. Allen's daughter and grandchildren are members of Maxwell's church and went to their home on the day of the shootings to comfort and counsel them.

"We all hope and pray that some answers come out, but unfortunately the only person that knows is no longer with us. He slipped into eternity," Maxwell said.

He shot and killed Gonzalez-Delgado around 9 a.m., then went a short distance and killed Pritchett (pictured, right) who began the company in 1980. Allen, at one time, was considered Pritchett's top assistant.

A few minutes later, Allen pulled over where another former co-worker was driving a farm tractor, exchanged words with him and fired a shotgun, authorities said. The victim, 66-year-old Mabrey, was in good condition.

Allen killed himself at his nearby home. Deputies recovered a .22-caliber rifle, a .410-small-bore shotgun and an unfired .32-caliber handgun.

Allen was the step-grandfather of Buffalo Bills running back C.J. Spiller.

Bills coach Doug Marrone said Spiller was excused from the team to go to Florida.

"Our thoughts and prayers go out to the victims as well as, you know, C.J. and his family in this situation," Marrone said Monday. "We're in communication. I don't have any answer of when he's going to come back."

Toby Kitchens, Spiller's high school football coach, knew Griffis and everyone else involved in Saturday's shooting. He described Griffis as a kind and caring family man.

"He always took care of his wife and stuff," Kitchens said. "He's going to be very much missed by his family and his community."

Griffis leaves behind a wife and several children -- the youngest a 5-year-old boy.

"We are saddened today on the loss of our dear friend and colleague David Griffis," Pritchett Trucking said in a statement. "David was a remarkable man who personified true work ethic and integrity and who was an integral part of our company -- and of our lives. Our thoughts and prayers are with his family and friends and David will always be a part of our family."

Union County Sheriff Jerry Whitehead said he'd known Griffis for many years and described him as a good person and friend.

"Just enjoyed talking to him over the years. He was really a nice guy," Whitehead said. "Tended to his own business, was never in any trouble, just a good guy. A hard worker, worked all the time. Took care of his family. He was a great family man."

To donate to the David Griffis' Give Forward fund, click here.