A Marietta man is facing prison for terrorizing and stealing from his mother and stepfather in their home, authorities said Friday.

Derek Baxter Emmett, 49, accepted a plea on several charges after placing his victims “in constant fear,” Marietta police said in a news release.

Police say the abuse went on for more than five years.

Derek Emmett frequently broke into the home of Barbara Emmett, 80, and Harry Swink, 78, and demanded money, police said, adding that Derek Emmett would threaten the couple with violence if money was not provided.

Even though the couple nailed their doors shut and tried other ways to keep him out, police said Derek Emmett would still break in to sleep or intimidate the victims.

Derek Emmett even invited his friends and transients to stay in the victims’ house, police said.

Barbara Emmett was recovering from back surgery and depended on a walker for most of the time the abuse occurred, police said. Swink was oxygen-dependent at the time and needed a wheelchair for mobility.

Derek Emmett pleaded guilty to two counts of elderly exploitation, two counts of elderly abuse, two counts of burglary, felony obstruction and second-degree criminal damage to property. He will serve at least four years of his 15-year prison sentence, officials said, and will not be eligible for parole.