Hans Thomas Reiser (born December 19, 1963) is an American convicted murderer, computer programmer, and entrepreneur. In April 2008, Reiser was convicted of the first-degree murder of his wife, Nina Reiser, who disappeared in September 2006. He subsequently pleaded guilty to a reduced charge of second-degree murder, as part of a settlement agreement that included disclosing the location of his wife's body, which he revealed to be in a shallow grave near the couple's home.
Prior to his incarceration, Reiser created the ReiserFS computer file system, which is contained within the Linux kernel, as well as its attempted successor, Reiser4. In 2004, he founded Namesys, a corporation meant to coordinate the development of both file systems.
In 1998, while working in Saint Petersburg, Russia, Hans Reiser reportedly selected a Russian woman from a mail-order bride catalog and arranged to meet her. He subsequently married Nina Sharanova (Russian: Нина Шаранова) who had joined the other woman on the date with Reiser as a translator. Nina was a Russian-born and trained obstetrician and gynecologist who was studying to become an American licensed OB/GYN. They had two children. Hans' father, Ramon, became suspicious of his new daughter-in-law when she took the title of CFO at Namesys at that time. Ramon was trained in military interviewing techniques and claimed that Nina lied to him when he confronted her about inexplicably fast shrinking reserves of Namesys. The Reisers separated in May 2004. Nina Reiser filed for divorce three months later, citing irreconcilable differences and alleging that their children "hardly know their father" because he was out of the country on business for most of the year, according to court records. She was granted sole legal custody of the children and shared physical custody of them with her husband. The divorce was never finalized.
Nina Reiser obtained a temporary restraining order against Hans in December 2004 after he pushed her, at the height of the divorce proceedings. She dropped the temporary restraining order in late 2005 because the heat of the divorce had chilled over time. In exchange, Reiser agreed to be bound by a one-year civil restraining order which prohibited him from "contacting, harassing or disturbing the peace" of Nina Reiser at her home or place of work and ordered him to stay at least 100 yards (91 m) away from her. In May, Nina Reiser alleged in court filings that her husband had failed to pay 50 percent medical expenses and childcare expenses as ordered by a judge and was in arrears for more than $12,000.
Nina Reiser was reported missing on September 5, 2006. She had last been seen on September 3, when she dropped the couple's two children off with Hans, at his mother's house where he was living at the time. She also failed to meet her best friend at her house later that evening.
Nina Reiser's 2001 Honda Odyssey minivan, with groceries inside, was found on September 9 on Fernwood Drive in Oakland's Montclair district, just east of the SR 13 Warren Freeway. It was reported by police that neighbors first spotted the parked minivan on September 5, the day she was supposed to pick up her children at school.
Hans Reiser's neighbors said that they saw him spraying water off something in the driveway for half an hour shortly after Nina went missing and said that his car — a 1988 Honda CR-X Si hatchback — disappeared shortly after, and his mother rented a car so Hans could drive hers. Police brought cadaver dogs in to search his property, but no human remains were found.
Following Nina Reiser's disappearance, which resulted in the removal of the Reiser children from the Reiser family, Hans Reiser attempted to obtain custody but was unsuccessful. Oakland police testified against Hans Reiser at the custody hearing, though they did not reveal the evidence on which they based their concerns.