Nick Reiner — the son of Rob and Michele Reiner, who’s been arrested on suspicion of murdering them — was missing for hours after his parents were found with their throats slit inside their Brentwood home … TMZ has learned.

Law enforcement sources say … after Rob and Michele’s daughter Romy found their bodies, she noted to police Nick had been living there and was possibly behind the murders.

When police responded to a call for a death investigation around 3:40 PM Sunday, Nick was nowhere to be found. Romy was the one who called 911 and told police her brother was “dangerous” and should be considered a suspect.

Romy told police Nick was not there when she arrived, insinuating he fled the scene. Police finally located and arrested Nick at approximately 9:15 PM Sunday.

Nick is currently in police custody, held without bail.

Beloved TikTok star Tucker Genal tragically passed away at the age of 31 by suicide.

Tucker’s brother, Carson, confirmed the news Monday on his Instagram, saying, “I don’t even know where to begin, You were my best friend and an even better big brother, my entire life I’ve spent looking up to you and trying to follow in your footsteps because you were always my hero.”

Carson continues to say … “I know one thing is for certain and that is that I will continue to spend the rest of my life looking up to you until we meet again. You were the kindest person I’ve ever met and the greatest brother that anyone could have ever asked for.”

Tucker was 31.

RIP

Nick Reiner, who is under arrest for the murder of Rob and Michele Reiner, checked into a Santa Monica hotel early Sunday morning, and left a trail of blood behind … sources with direct knowledge tell TMZ.

Nick checked into The Pierside Santa Monica around 4 AM Sunday, using his credit card. His check-in came hours after he got into a heated argument with his father at Conan O’Brien‘s Christmas party.

Eyewitnesses who saw Nick check in say he seemed “tweaked out”, but there were no visible signs he had been in a violent confrontation — we’re told definitely no blood stains or cuts on his body.

LAPD Robbery-Homicide detectives went to the hotel Monday to gather evidence and also interview employees.

Nick was eventually tracked down and arrested around 20 miles away in Exposition Park, near downtown Los Angeles.

TMZ broke the story … sources told us Nick was acting very strange at Conan’s party … not interacting with guests, and his attire was out of place … it was a pretty ritzy event, but Nick was rolling around in a sweatshirt and seemed high on something.