MARTINEZ (CBS SF) — A former Walnut Creek police officer was sentenced Friday to a year in jail and three years of probation with the possibility of electronic home detention two months after donning a mask and beating a woman with a baseball bat in Richmond in August.

Gregory Thompson, 54, received the sentence in a Martinez courtroom Friday afternoon in connection with the Aug. 16 assault that sent a San Jose woman to the hospital. He has the option to apply for electronic home detention and could see his sentence reduced to six months with good behavior, according to Contra Costa County Deputy District Attorney Barry Grove.

The Martinez resident and 30-year Walnut Creek Police Department veteran pleaded no contest last month to charges of felony assault with force likely to cause great bodily injury, felony vandalism and being armed in the commission of the crimes.

At Thompson’s arraignment, Grove said the police officer was eligible for up to five years in prison but that the district attorney’s office planned to seek a one-year jail sentence.

The prosecutor said that given Thompson’s lack of criminal history, the sentence is “probably fairly typical and may be on the heavy side.”

Authorities said Thompson went to his father’s vacant house on Clinton Avenue in Richmond in the early morning hours of August 16 with the knowledge that the home had recently been burglarized.

Once there, Thompson saw a woman walking in the area and apparently believed she was an intruder. He then donned a ski mask and armed himself with a baseball bat and attacked her with the bat, according to police and prosecutors.

Police responded around 2 a.m. to several reports of a woman screaming and a man with a baseball bat. Another woman was also injured after she intervened and tried to stop the attack, according to police.

Officers found the victim hiding in some bushes and Thompson sitting in his car nearby.

Police said when officers contacted Thompson, he identified himself as a police officer but was not wearing a police uniform or in a marked police vehicle. Officers searched the car and found a baseball bat, mask, two guns and zip ties in the car.

The victim was taken to a hospital to be treated for injuries that were not considered life threatening and is no longer suffering from any physical injuries related to the attack, according to Grove.

Authorities said the woman had been walking in the area after her car broke down.

Thompson was arrested and taken to county jail in Richmond, where he was released on bail the following day, according to police.

He was placed on paid administrative leave from the Walnut Creek Police Department after his arrest and was later fired.

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