Mrs. LaRoche was the mother of J.J. LaRoche. She makes no physical appearance on the show but is mentioned multiple times during the Season 5 episode Red and Itchy.
She is first mentioned when her son asks Jane to discretely retrieve the ominous tupperware box first seen two seaons earlier (Redacted).
According to Van Pelt’s research she was physically and sexually assaulted nine years prior to the episode by a man named Scott Saynay. The attack lasted 2 hours and the victim took her own life 3 months after the incident.
At the end episode it is implied that JJ broke into Saynays house the night before his trial, sedated the man and cut out his tongue - which in turn would be the content of that ominous tupperware box.