NFL line judge Carl Johnson -- the former head of officiating for the league -- is under investigation for an alleged pattern of domestic violence in Louisiana, though he's adamant the accusations are BS, TMZ Sports has learned. 

Johnson's accuser is a 49-year-old woman who told police she and Johnson had been living together in 2016 when the NFL official became aggressive. She claims Johnson first got violent in December and during the incident, Johnson hit her so hard, he busted one of her breast implants.  

The woman claims she went to the NFL in March hoping the league could help her out. Unclear what happened next but a few months later, she went to police.

Court officials in Louisiana confirmed the accuser requested a temporary restraining order against Johnson and it was granted. But a request to make the restraining order permanent was rejected at a later hearing.  

But it's not case closed ... a rep for the Lafourche Parish Sheriff's Office confirmed to TMZ Sports that the case involving Johnson and his accuser is still under investigation.  

Sources connected to the case tell us Johnson has denied all allegations of domestic violence and vows to continue to fight the case. 

We spoke with the accuser who claims she has photos and audio recordings to back up her allegations.

Of course, in the wake of the Ezekiel Elliott situation -- the league believes it has the right to impose punishment on NFL players and other staff for domestic violence without a conviction in a court of law. Elliott feels differently. 

We reached to the NFL to see if it was investigating Johnson -- so far, no word back. But we do know Johnson has been working NFL games. He was the line judge during Monday Night Football in Week 1. 

TMZ Sports reached out to Johnson who told us, "No comment."