Cindy Crawford, Rande Gerber Gather at Kaia's L.A. Home, Weeks After Presley's Death

Cindy Crawford and Rande Gerber look like they're leaning on family ... visiting with daughter Kaia Gerber as they continue to cope with the heartbreaking loss of their son and brother, Presley Gerber.

The trio was photographed meeting up at Kaia's Los Angeles home on Tuesday morning, a little over three weeks after Presley's shocking death.

The family has largely kept things private in the wake of the tragedy, with loved ones and close friends rallying around them during an incredibly difficult time.

We broke the story ... Presley died at a sober-living facility in Santa Monica on September 20 ... he was found dead hours after he checked in.

Sources told us Presley had a 24-hour sober coach with him, who dropped him off at the sober home the night before he was found unresponsive in a bedroom.

We're told Presley showed up to the facility -- Resolutions Living -- seemingly high on drugs, despite it being a cardinal rule in the rehab world not to admit patients who are under the influence.

Our sources tell us the sober coach called Resolutions in advance to give them a heads-up about the state he was allegedly in ... however, we're told the facility welcomed him anyway.

We asked the owner of Resolutions Living -- Dr. Reza Navabi -- to answer the looming question ... why was Presley admitted into the facility, even though they were warned he wasn't sober?

Navabi was mum on the situation.

Police are investigating the death as a suspected overdose, though his official cause and manner of death have not been determined.