The incident has rattled Leo, who portrays the gruff Detective Kay Howard on the NBC cop drama, filmed on location in Baltimore. "I fear for the safety of my son and my safety," Leo wrote in a police complaint, adding that Heard "is stalking my son and must be stopped before something else happens."
Her boyfriend, John Russell, said that Heard assaulted him in front of the son's Baltimore school. Russell also complained that Heard harassed him with threatening phone calls.
The 50-year-old Heard was charged with stalking and assault Tuesday by Baltimore police and freed on $50,000 bond. He faces arraignment on December 17.
Leo had received an ex-parte order against Heard prior to the alleged assault. "It was for protection from him," said Agent Ragina Cooper of the Baltimore police.
After the relationship between Heard and Leo soured in 1994, he was denied custody of their son. A judge in New York said Heard lacked "temperament in parenting skills" and also cited Heard's history of physically abusing Leo.
His agent and her manager said neither actor would comment on the case.