Yolanda Davis, 44, is accused of stabbing her boyfriend, Johnny Jackson, last week at the apartment they shared, the Gary (Ind.) Post-Tribune Tuesday.
Jackson, 54, was adopted by Jackson family patriarch Joseph Jackson as a teenager and performed with the Jackson 5 for 15 years, the Post-Tribune said. Other reports said he was a first cousin to the singing clan.
Janet Jackson is paying for her adoptive brother's funeral, the Post-Tribune said.
The news of his death came "as a real shock to the Jackson family," Jackson family attorney and spokesman Brian Oxman told the Post-Tribune.
"He was like a brother to all of them," Oxman said. "He was a part of their youth, and now that is gone."