Apgar lived with her husband on the Tanuga IV research station. She spent a lot of time alone, as Nel worked very hard on his experiments. She knew her patience would pay off, however, as she had great respect and admiration for him.
When the United Federation of Planets sent the USS Enterprise-D to put together a status report, she met Commander Riker. She became infatuated with him and flirted with him. Nel found out and threatened to file a complaint. He sent Apgar and his assistant, Tayna to Tanuga IV after the visit. Shortly, they found out the station had in a mysteriously exploded and Nel had died.
After her husband was killed, she claimed in her deposition that Riker had killed him, because he had caught Riker assaulting her. Manua believed that Riker tried to take advantage of her sexually, and that he killed her husband, because Dr. Apgar threatened to file a complaint. Her perspective of the events leading up to her husband's death were programmed into the holodeck, under the name Manua Simulation One, which recreated the seduction and the fatal explosion, according to her perspective. Riker contended that Mauna tried to seduce him and that he turned her away. Dr. Apgar walked in on them and misunderstood what was going on. It was later proven that Apgar had accidentally killed himself in an attempt to kill Riker. The attempt at murder was not because Apgar was jealous, but because he was worried that Riker discovered that he was creating a weapon. (TNG: "A Matter of Perspective")