Killed Nick Corelli because she blamed him for Steve's death
Jo was married to Duke Johnson, an abusive drunk. To keep her children from an abusive home she gave her sons Steve and Billy away, but kept her daughter Adrienne, believing that Duke would not hurt her. She followed Adrienne to Salem to find Steve, because Adrienne was terrified that one day, Duke would beat her to death. Duke followed her to Salem, and threatened to hurt Adrienne. Duke eventually raped Adrienne, who shot and killed him, even though Steve originally tried to take the blame.
Jo took a job working for Dr. Neil Curtis as his maid, and Steve finally began to trust his mother, even though he still harbored some resentment for her giving him away years earlier. While working for Neil Curtis, she was intrigued by some of his houseguests...Harper, Anjelica, and Jack Deveraux. She and Jack formed an immediate bond, and when she saw the ring that he was going to give Kayla, she knew he was her son Billy...years earlier she had given that ring to Camille, the first Mrs. Deveraux! But rather than devastate Jack, who had no idea he was adopted, she kept quiet, content to just know her son.
Harper attempted to get Jo out of Jack's life, but Neil Curtis begged her to stay on at his home, so she did. Steve eventually realized the truth, but she begged him to keep quiet. When Jack was diagnosed with Hodgkin's, Steve pushed Kayla toward him. Jack and Kayla wed, and Steve's grief allowed mother and son to finally connect. He was also there for her when Jo had a brief bout with breast cancer. Shortly after, Jack learned the truth about who she was to him, and although he was angry at first, soon he started to thaw toward her. While Neil married Anjelica, Jo got over her heartbreak (she was secretly in love with him) by sponsoring April Ramirez, who was just coming to terms with her alcoholism. Jo found herself in great danger when Earl, her husband Duke's twin brother, came to Salem. He wanted revenge for Jo putting him in prison years ago. Luckily for her, Steve stopped Earl before he could hurt her too badly, and Earl went back to jail.
Jo, Steve, Jack, and Adrienne were just becoming a family (which took a lot considering that Jack had raped Kayla, whom Steve had later married) when Steve was killed by a bomb. Shortly after, the police's top suspect, Nick Corelli, also wound up dead, with Jo and April as suspects. At the same time, Jo also revealed to Neil her long-time crush on him, and although she wasn't sure if she could, she agreed to stay in the house. She did her best to help Jack and his new girlfriend Jennifer find out what had happened, but things broke down when Jack confronted her with killing Nick...April wasn't guilty, she was trying to protect Jo! Jack convinced his mother to plead temporary insanity, and she ended up spending some time in Bayview. By the time she got out, Neil Curtis had already left Salem.
Jo got a small apartment in Salem, and threw herself wholeheartedly into being Jack's mother, who by this time was her only child left in Salem. She was also a devoted grandmother. When Jack believed his Hodgkin's was flaring up again, she even helped him in his crusade to find Jennifer a new husband, and also impersonated Leslie Morgan when Jack tried to publish a manuscript he found in the attic of his and Jennifer's house. Jo began dating Vern Scofield, one of Jack's co-workers at the Spectator, but Jo's purpose in Salem was at an end when Jack disappeared from town, believing he'd caused Abby's aplastic anemia. She left for Texas to be with Justin and Adrienne. She returned to Salem when she heard that Steve found alive and living with amnesia.