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San Bernardino (FOX 11/ AP) - A 70-year-old, off-duty sheriff's deputy braked to avoid two dogs and was rear-ended by a driver who then got out and delivered a fatal punch, police said Wednesday in announcing a murder charge against the man.

The attack occurred on New Year's Eve and San Bernardino County sheriff's Deputy Lawrence Falce was taken off life support two days later.

Surveillance video from a nearby store captured the encounter, which lasted only about a minute.

After the fender-bender, Falce and a man police identified as Alonzo Leron Smith got out of their cars, exchanged words and motioned at each other. Smith then delivered a single punch to the face and Falce fell backward, his head hitting the pavement.

"We believe that he was knocked unconscious almost immediately and he never did regain consciousness," San Bernardino Police Chief Jarrod Burguan said at a news conference.

Smith got back in his Ford Explorer and the video showed a truck ramming it to try to keep him from driving off. Smith managed to drive away but was arrested hours later, police said.

The 30-year-old San Bernardino man pleaded not guilty on Wednesday to murder with special circumstances.

Smith is a gang member who has spent much of his adult life in and out of lockups. In 2015, he was released after serving two years of a 12-year sentence for selling marijuana, San Bernardino County District Attorney Michael Ramos said.

"This person needs to spend the rest of his life in prison," Ramos said.

Falce worked 36 years as a deputy sheriff. He also coordinated search-and-rescue volunteers.

"He was a mentor and a great partner to countless deputies who had the privilege to work with him," Sheriff John McMahon said.

Falce was the oldest member of the 3,700-member department, which does not have a mandatory retirement age but requires deputies to pass training exercises several times a year to ensure they still can do the job, spokeswoman Cindy Bachman said.

"He spent all of those years basically patrolling the community he lived in," she said.

Falce began his career with the San Bernardino County Sheriff's Department in 1981 as a deputy sheriff. Falce started his career working in corrections at the Glen Helen Rehabilitation Center and the Central Detention Center. The 36-year veteran worked patrol at Central Station for the past 32 years. Before joining our department, Falce served his country in the Army. He prided himself as being a lifelong public servant, who cared deeply about this profession.

Falce was loved by his peers and the community members he served. More importantly, he cared about so many people he called family.

Falce is survived by his sister, Marjorie, and his girlfriend of many years, Deborah. He also leaves behind many extended loved ones.