"He faced it, didn't shirk it," Miccio told ABCNews.com. "He received treatment for it. It was a day-to-day thing that was woven into his fabric. It never affected his work. Maybe he was a little more grouchy than usual. But he was able to deal with it.
"I don't think anything happened," Miccio said. "There was no trauma. It was just something he dealt with."
Koenig's father concurred on his Web site, where he has been posting information about his missing son.
"I think it's something that has been a part of his makeup for a long time. There's no single trauma. There's no episode. There's nothing of that nature," he wrote.
He added "drugs were not an issue."
Miccio said Koenig wasn't married but dated. "He had an active social calendar," he said, "and was extremely close to his family."
But it appears that his family and friends were not aware until after he left for Vancouver that he may not have planned to return to California.
Miccio said Koenig sold or gave away all of his possessions, gave 30-days notice to the landlord of the Venice, Calif., apartment that he rented for 14 years and told a mutual friend that he was going to Vancouver to "start over."
While Miccio was out of town, Koenig dropped off a bag of belongings and gifts at Miccio's door. "He hooked it on my doorknob – a plastic bag of video tapes and stuff we had worked together on. Even gifts I had given him. He just returned everything, with no note or anything."
Judy Koenig told reporters the last time she heard from her son was when he left a message on Feb. 8 or 9 asking how she was recuperating from recent surgery.
Longtime friend Jenny Magenta, who was the last to see him in Vancouver, said Koenig came to stay with her on Feb. 10, after visiting mutual friends in Toronto. She last saw him on the evening of Feb. 14.
"That night I went to bed and in the morning he was gone," Magenta said.
She said Koenig left a note that said simply, "Thank you, Andrew."
According to his father's Web site, Koenig's phone received a text message and he made a bank transaction.
Police have scoured the 150 miles of trails of a 1,000-acre park since last weekend but have come up empty.
Miccio said Andrew has ventured solo into the Vancouver woods before but usually in the summertime and he's always been in contact with family and friends.
"I don't want to speculate on what may have happened," Miccio said. "My hope is he went into the woods and went off the grid."
Jason Stine from ABC News contributed to this report.