(CNN) -- A hunt for a missing FBI agent stretched into its fifth day Tuesday after an intensive search of rugged terrain near Los Angeles failed to turn up anything.
Special Agent Stephen Ivens appeared to be distraught and may have been suicidal, FBI spokeswoman Laura Eimiller said, citing interviews with family members and evidence collected by investigators. She declined to elaborate.
Ivens, who works on counterterrorism cases, was last seen by family Thursday night, a police statement said. His FBI-issued service revolver is also missing, Eimiller said.
Investigators and volunteers working for local police, as well as about 50 FBI agents, had searched the rugged Verdugo Mountains after bloodhounds tracked his scent in the area, according to authorities.
Authorities had since scaled back, but have not ended, the mountain search, Eimiller said on Monday.
"We're not ruling out that he may have gone in a different direction," she said.
Ivens is white, 6-feet-tall and weighs approximately 160 pounds. He wears prescription glasses, police said, and is described as having brown hair with a receding hair line and brown eyes.
Ivens is known as an avid hiker and runner, CNN affiliate KABC repoorted. He has a wife and a 1-year-old baby, the affiliate reported.