According to Extra, Mark Anthony Burk has filed a lawsuit against Johnson, claiming that she and Oz's Chuck Zito showed up at his home in January 2009 and threatened him with a gun.
Court documents allege that Johnson tried to force Burk to sign a separation agreement, which would have paid him $2,000 (£1,301) to get out of her home, but he fled to a neighbour's house.
"It is our understanding that Mr Burk has been convicted of making terrorist threats against Ms Johnson and is presently serving that sentence," said Johnson's rep in a statement.
"We also understand that since his conviction, he has been found in contempt on three different counts of wilfully violating probation. Ms Johnson is in fear for her safety, but she's actively working with law enforcement to resolve this situation."