Nobel prize-winning mathematician John F. Nash Jr., subject of Ron Howard’s Oscar-winning film A Beautiful Mind, was killed Saturday in a car crash in New Jersey along with his wife, Alicia. Nash was 86.

The couple had just returned to the US from Norway, where Nash was awarded the Abel Prize by The Norwegian Academy of Science and Letters. The driver of their taxi lost control of the vehicle during an attempt to pass another car, hitting the guard rail and a third vehicle, local law enforcement said. Nash and his wife were ejected from the car.

Born in 1928 in Bluefield, West Virginia, Nash attended undergraduate school at the Carnegie Institute of Technology (today part of Carnegie-Mellon), and received his PhD from Princeton. For several summers in the 1950s he was a consultant for the RAND corporation, and eventually went on to teach at both the Massachusetts Institute of Technology and much later in life, Princeton.

Considered one of the greatest mathematicians of the 20th century, Nash’s brilliance was apparent early on, and in fact, the letter of recommendation to graduate school written for Nash by his mentor consisted of a single sentence – “This man is a genius.” During the 1950s he had groundbreaking achievements in several disciplines, including differential geometry, and partial differential equations. But it was his pioneering work in game theory that would earn him his greatest acclaim.

His 1950 doctoral dissertation on non-cooperative games described what came to be known as the Nash Equilibrium, a situation in which it is not possible to predict the outcome of multiple decision-makers if their decisions are studied in isolation from one another; instead, the decision-making of all parties must be taken into account. The concept has been applied to a number of varying fields, including geopolitics, sports, and business. For this work, Nash would eventually win the 1994  Nobel Prize in Economic Sciences.

AbeautifulmindNash’s personal life was famously complicated and troubled, however. In the early 50s, he fathered a child out of wedlock, but abandoned the mother and child after she became pregnant. He also had same sex relationships, and in 1954 was arrested for indecent exposure in Santa Monica, California, as part of an entrapment operation aimed at gay men, an event that cost him his consultancy at RAND. He married his wife Alice in 1957, though their relationship and his career was almost derailed early-on by Nash’s struggles with mental illness. Diagnosed with paranoid schizophrenia in 1959, he would spend the 1960s in and out of psychiatric hospitals, often disappearing for months at a time. During this period, he and Alicia divorced, though the two remained close.

Nash began a slow recovery after 1970. Boarding with his now ex wife in New Jersey, he stopped experiencing delusional episodes, though he continued to be a solitary and somewhat unapproachable figure, known more for wandering the Princeton campus, where he became known to students as “the Phantom of Fine Hall”. By the 1990s, however, he had recovered enough that he was able to resume teaching and accept his Nobel Prize. The Nashes rekindled their relationship in the 1990s, and remarried in 2001.

Nash’s experience with and eventual recovery from mental illness was dramatized in Ron Howard’s 2001 film, which starred Russell Crowe as Nash and Jennifer Connelly as Alice. Though it received numerous accolades, including four academy awards, the film was also criticized by some for omitting certain aspects of Nash’s life, including his first child and bisexuality, and for oversimplifying the Nash Equilibrium.

Nash is survived by his sons John David Stier and John Charles Martin Nash, and his sister, Martha Nash Legg

As news of Nash’s death became public, tributes poured out. On Twitter, Ron Howard and Russell Crowe expressed their condolences.