"He will be missed very, very much," the Nobel Prize winner's son John David Stier tells PEOPLE

By Harriet Sokmensuer
Updated May 25, 2015 03:10 PM
Credit: Fred Prouser/Reuters/Landov

Family and loved ones remain in shock over the sudden deaths of renowned mathematician John Nash and his wife, Alicia, who were killed Saturday in a car accident in New Jersey.

On Monday, Nash’s older son, John David Stier, opened up to PEOPLE about his parents’ passing, and the impact that the mathematician – who was the subject of the Oscar-winning film A Beautiful Mind – had on him.

“My father was a very special and unique person in my life,” Stier tells PEOPLE. “He will be missed very, very much.”

He adds, “It’s very saddening to hear what happened to him, very saddening, and a deep shock.”

“I heard about it yesterday, the day after it happened,” Stier says.

Nash and his wife were ejected from a 2007 Ford Crown Victoria taxicab when the driver, Tarek Giris, 46, struck the rail at the side of the highway, and then another vehicle, while attempting to pass the car in the center lane.

The ongoing investigation suggests the couple were not wearing seatbelts at the time of the accident, and Giris has not been charged at this point in the investigation.

Nash’s life story inspired the 2001 film A Beautiful Mind, which starred Russell Crowe and won the Oscar for Best Picture.

John Forbes Nash Jr., Subject Of A Beautiful Mind, Dies

In 1994, Nash was awarded the Nobel Prize for Economics for his revolutionary work in the field of game theory.

He is survived by two sons and his sister.