"He sounded despondent," Koening's father says of his son, who was visiting Vancouver

On Feb. 16, Walter Koenig received a note from his son Andrew, which caused his father to grow concerned about his whereabouts.

“He sounded despondent,” says Walter, who spoke to PEOPLE from his Los Angeles home. “Nobody has seen this [note] but my wife and I.”

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Andrew Koenig, 41, who starred as Boner on the late 80s sitcom Growing Pains, was set to arrive in Los Angeles on Feb. 14 after a trip to Canada, according to the Vancouver Police Department.

“He went to visit some friends in Toronto and after there, he went to Vancouver,” says his father. “It s a place where he felt very comfortable. He lived there for a few years.”

Andrew still hasn t returned to his Venice, Calif., residence. His father says there wasn t a specific situation that would ve prompted his disappearance.

“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,” says Walter, who added that drugs were not an issue.

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The former child star, who discovered Vancouver while filming an episode of 21 Jump Street in the late 80s, returned to live there in the early 90s and would often take walks in the city s Stanley Park, according to police.

He had recently finished shooting a trailer for a feature film that he wanted to direct, says his father. Andrew had also grown into an outspoken environmentalist and human rights activist, as well.