YARMOUTH, MASS. (WHDH) - A Somerville man accused of shooting and killing a 32-year-old Yarmouth police officer Thursday has been ordered held without bail.

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Thomas Latanowich, 29, who prosecutors said has more than 100 criminal charges on his record, pleaded not guilty Friday in the First District Court of Barnstable. He is facing a murder charge in connection with the shooting death of canine officer Sean Gannon.

Dozens of police officers filled the benches of the courtroom as Latanowich was arraigned.

Prosecutors say Gannon was shot in the head while he and other officers attempted to serve a probation warrant on Blueberry Lane. He was rushed by ambulance to Cape Cod Hospital, where he was later pronounced dead.

Sources have told 7News that Latanowich was hiding in a closet in the home’s attic before he shot Gannon in the head.

Gannon’s K-9 partner, Nero, was also shot and was taken to a veterinary clinic in Dennis to be treated.

Latanowich, who has been labeled a “career criminal,” has more than 100 arrests for violent crimes. The Massachusetts Probation Service says Latanowich’s conditions of probation included random drug screens and a mental health evaluation, among other things.

An official told 7News that Latanowich was not home for a probation visit on April 4 and that he failed to appear for a drug test on April 5. A warrant was issued for his arrest on April 6.

Latanowich had been sentenced on July 26, 2010, to 4-5 years in prison for assault with a dangerous weapon. He has also been charged with heroin possession, witness intimidation and receiving stolen property, among other things. He was released on parole in Nov. 2013, returned to custody in June 2014 for violating parole and then released days later.

Cape and Islands District Attorney Michael O’Keefe said Latanowich had a drug conviction overturned as a result of the Annie Dookhan scandal.

Latanowich’s five-year probation period was slated to end on Nov. 1, 2018.

This is a developing news story, 7News will post additional information as it becomes available.

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