"He shaved off his beard. He had some damage to his car. You know, it's just one thing after another. It just seemed kind of strange," said neighbor Judy Quinn.
Neighbors said Forsberg, 61, told them his wife had gone away to visit friends.
"Usually we would see her sitting on the driveway, but because he said she had gone to see friends, it wasn't a big deal," said another neighbor, Nicole Kontoff.
Investigators executed a search warrant at the couple's Rancho Santa Margarita home on Tuesday, but when they went back a second time to interview Forsberg about his wife's disappearance, he was not there.
"He hasn't been to work in a couple of days, which is unusual. There's been no cell phone activity on his cell phone. Needless to say, there have been no cell phone or financial transactions on Marcia's, the missing person," said Jim Amormino of the Orange County Sheriff's Department.
Authorities are not calling Forsberg a suspect, but only a person of interest. They think he may be driving his wife's 2001 silver Volkswagen, which has California license plates 4TIM403.
Deputies said they hope to find Forsberg, so that they could be one step closer to finding out what happened to his wife.
The Forsbergs have been married for 39 years.
Anyone with information was asked to call the Orange County Sheriff's Department (714) 628-7170.