(CNN) A Massachusetts state trooper was suspended without pay indefinitely Friday pending an investigation into whether he made racist and obscene comments on a police-themed website.

Massachusetts State Police named Trooper Matthew Sheehan in a statement Thursday, saying he faces an internal affairs investigation over the online posts.

He has been on administrative leave following his role in a shooting that left an ATV driver injured last Saturday.

Dave Procopio, a spokesman for the state police, said in an email to CNN that "the Department has opened an Internal Affairs case to determine whether Trooper Sheehan is the author of certain posts made to an online forum."

Further action could be taken at the end of the investigation if it's warranted, Procopio said, adding, "The tone and content of the posts in question are offensive and are contrary to the standards of conduct expected by the State Police of its members."

"If those posts were issued by someone who's a member of the state police, they are clearly a violation of [the] code of conduct and he or she should be fired," Gov. Charlie Baker told reporters Thursday.

Several posts, which date back to 2012, include disparaging comments against people of color and others mentioned in news stories about crime. Some posts also appeared to praise officers in police-involved shootings.

Richard Rafferty, an attorney representing Sheehan on behalf of the State Police Association of Massachusetts, said in a statement Friday the decision to suspend Sheehan "illustrates the disparate treatment between the rank and file of the Massachusetts State Police and their leadership."

"Here, we have a knee-jerk reaction by a Colonel under political pressure to suspend a trooper without pay," Rafferty wrote, "virtually putting him and his family on the street, all without an investigation into the allegations of comments made in a chat room."

An attorney representing Sheehan on behalf of the State Police Association of Massachusetts has not responded to CNN's requests for comment.

CNN reviewed the comments made by Big Irish, but has not been able to independently verify that it is Sheehan's user name or account.

In a June 2012 post, the Globe says Sheehan wrote about a mother who turned in her 14-year old son to police to face burglary charges: "She probably did it so she wouldn't lose her EBT benefits. Where are the $10,000 in jewelry???? Melted down and sent back to the Domonican (sic) Republic.!!!!"

In an August 2012 post about a man who was fatally shot by police after a foot chase, the poster the Globe has identified as Sheehan wrote: "I guess this POS won't be heading to the pols (sic) in November to vote and keep his EBT card.!!! What are they going to do with his newly acquired Barber College certificate??" News reports showed a picture of an African-American man who'd been shot.

In a September 2015 post about a shooting near a festival celebrating African history, the Globe says Sheehan posted, "Just another peaceful 'Black Lives Matter' festival!! Nothing to see here so please move along!! Can't wait for the next one it'll sure be a bang!!!"

In the article, the Globe said it alerted the State Police to the postings.

Gov. Baker said the comments don't appear to be isolated because "those posts, and the vulgarity of them date back five, six, seven years."

"This is an ongoing collection of thoughts and comments that have no place in law enforcement, no place in public discussion, no place in our community period," he added.

In the shooting on Saturday, the Suffolk County District Attorney's Office said one trooper discharged his weapon as state police tried to stop and arrest a group reportedly riding motorcycles, ATVs and dirt bikes in an unsafe manner.

One rider suffered a minor injury to his foot. Investigators are trying to determine how he was injured, prosecutors said.

CORRECTION: This story has been revised to state that a Suffolk County District Attorney's Office news release said one trooper discharged a weapon during the encounter with a group reportedly riding motorcycles, ATVs and dirt bikes in an unsafe manner. The release did not name Matthew Sheehan as the trooper who discharged a weapon.