Hogan was in a car in the city of Walnut Creek on Sunday evening with his wife Janet Hogan, 75, and their son Tim Hogan, 40, when their 2000 Honda Accord crashed near Mount Diablo Boulevard and San Miguel Drive and plunged into the rain-swollen creek, police said.
Tim Hogan, a San Diego resident, was trapped inside the car and died at the scene, police said.
Janet and James Hogan, both Walnut Creek residents, were able to escape, but were quickly swept away in the current.
A California Highway Patrol helicopter was able to lower a rescue swimmer from the Contra Costa County Fire Protection District into the water and pull Janet Hogan to safety.
James Hogan, however, disappeared after being seen floating face down in the water near Bancroft Road.
The sheriff's office conducted an extensive search Monday with more than 50 members of its search-and-rescue team, K-9 units, helicopters and boats. Crews scoured the 11.3-mile length of Walnut Creek between Bancroft Road and the Sacramento San Joaquin-Delta, but found no sign of James Hogan's body.
The ground search was called off Monday evening. On Tuesday, the sheriff's office searched the area again by helicopter, but again found no sign of Hogan.
During a helicopter search Wednesday, two members of the sheriff's office dive team aboard the helicopter spotted Hogan's body shortly after 6 p.m. An autopsy today confirmed that he drowned.
James Hogan had volunteered with the sheriff's department for almost 16 years at the Alamo station, where he coordinated other volunteers, Lee said.