Niver was last seen in Superior Township, Michigan on August 7, 1993. She moved out of the residence she shared with her former boyfriend, Gregory Agnew, the day prior to her disappearance.
Gregory later told police that the breakup had been his idea because Niver was jealous, but according to the couple's friends, it was Gregory who was the more jealous of the pair. Niver's sister said Gregory had been violent to Niver, and that Niver was afraid for her life.
Niver drove to Gregory's home at approximately 2:30 a.m. to retrieve some of her personal belongings. He told authorities that they spoke at his house and she departed shortly afterwards. She has never been heard from again.
Her vehicle, a borrowed 1979 Mercury Marquis, was discovered abandoned on Cornell Street in Ypsilanti, Michigan at approximately 11:00 a.m. that morning. The car was illegally parked in the middle of the road and the keys were in the ignition with the engine running. There was no sign of Niver at the scene.
Gregory has long been a suspect in Niver's disappearance, but he was never charged. He accused the police of harassing him and sued them, and was awarded a $45,000 legal settlement. A photo of him is posted with this case summary.
Just four days after Niver's disappearance, a friend of hers, Martha McGeorge, took guardianship of her children for three months. Police approached her and asked her to assist them with the investigation, and Martha agreed to wear a recording device and get Gregory to confess to his involvement in the case. Instead, Martha started dating Gregory. They married in 2014 and she took his surname.
By 2018, Gregory and Martha were in the process of a divorce, and Martha had made domestic violence allegations against him. The police contacted her and asked her again for assistance in Niver's case. She declined to help them, but told Gregory about their inquiries. Just weeks later, Martha was murdered in her home: strangled, beaten about the head, and injected with heroin and fentanyl.
Gregory was convicted of his wife's murder in 2019. Details about Niver's disappearance were brought up at the trial, and one of Gregory's other ex-girlfriends testified that about his violence towards her. The ex-girlfriend said Gregory was a jealous partner but did not become violent until she told him they should break up. Then he held her down, duct-taped her to a bed, electrocuted her repeatedly over a period of hours, and repeatedly sexually assaulted her. She was pregnant at the time.
Investigators believe Gregory killed Martha to keep her from talking about what she knew about Niver, and to keep her from getting their home in their pending divorce. He was sentenced to life in prison without parole for Martha's murder and his conviction was upheld on appeal, but he has never been charged in Niver's case.
Foul play is suspected in Niver's disappearance due to the circumstances involved. Her case remains unsolved.