Dog the Bounty Hunter Has Chill Birthday at Benihana, No Sign of Moon

Dog the Bounty Hunter's tumultuous week of family drama was capped off with a birthday dinner filled with emotion ... but interestingly, without ONE key person.

Sources close to the reality TV star tell TMZ ... Duane celebrated his 67th birthday Tuesday with a small group of family and friends at a Denver Benihana. We're told everyone at the table shared stories ... including some about Beth Chapman, which made Dog a little weepy.

The guests included his daughter, Bonnie and her husband, his son, Garry, his advisor and Justin Bihag ... one of his employees who's run into legal trouble lately.

TMZ broke the story ... Justin was arrested for allegedly violating probation. Dog's other daughter, Lyssa, reportedly outed Justin to cops, but she's having some legal trouble of her own now.

It's a messy situation, and it all ties back to Justin's mom, Moon Angell.

In case you haven't heard, Moon is a longtime friend of Dog and Beth who's been accused of starting up a romantic relationship with the guy in the wake of Beth's passing. They've both denied anything physical is going on, insisting their relationship is platonic.

They even went on the 'Dr. Oz Show' and put on a "test" proposal to definitively confirm nothing fishy's going on between them, despite Lyssa's suspicions.

Interestingly enough, Moon was NOT at Dog's birthday dinner -- even though Justin was. We're told Dog loves the kid like one of his own and continues to look out for him.