Andrew Koenig's Parents Walk Out on Larry King

Fears for Growing Pains actor Andrew Koenig are increasing after his parents abruptly left the Larry King Live studio last night, just minutes before they were set to appear.

"For some reason unbeknownst to anyone, Walter Koenig, the father of the missing Andrew Koenig, and Andrew's mother Judy Levin-Koenig...left the studio in Vancouver," Larry King said on the air, reports E! Online.

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"We checked them out, they were prepared to go on, I said 'hello,' they said 'hello.' We said we'd be on in two minutes, they said 'fine.' And they got up and left, for reasons unknown."

Family and friends are hoping their departure wasn't prompted by bad news.

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Andrew's sister Danielle appeared on Larry King Live last night to discuss her brother's disappearance.

"It's just very upsetting," she said. "My brother does suffer from depression, so we're very, very worried about him, and we just want to find him."

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Walter Koenig, who played Chekhov on the original Star Trek, and his wife appeared on the Today show yesterday morning and then issued a statement directly appealing to their missing son.

"I just want to know you're OK," Walter said. "If it means you just want to stay here, that's OK. You don't have to come back. Just let us know that's your intention."