A family member says they saw Matt Brown near the Washington river where an unidentified man later disappeared … and the sighting happened just hours before police launched a search.

The former “Alaskan Bush People” star’s relative tells TMZ … they spotted Matt around 8 AM Wednesday near Driscoll Island Wildlife Area off Highway 97 in Oroville, Washington … less than a mile from where a witness later reported seeing a man swept away in the Okanogan River.

According to the relative, the location is a campground and fishing hole Matt is known to frequent. The family member also tells us Matt owns a firearm.

The sighting adds a new piece to the mystery surrounding Matt’s whereabouts after his brother, Bear Brown, publicly expressed fears he may be dead.

As TMZ reported … Bear posted an emotional TikTok video Thursday saying he was told Matt had been seen near a river and was later observed floating in the water. Though Bear said he couldn’t independently verify the account, he acknowledged the circumstances appeared to point to his brother.

The Okanogan County Sheriff’s Office told TMZ … a 911 caller reported seeing a man sitting in shallow water along the Okanogan River south of Oroville on Wednesday. Authorities say the caller looked away briefly, then turned back to find the man face down in the river before he was swept away by the current.

Despite a search by police, firefighters, and EMS personnel, the man has not been located. Authorities said Friday the search would resume when weather conditions improve.

Last week, Matt posted a YouTube video of himself allegedly intoxicated and wandering around naked with what appeared to be a gun in a public park in Washington state.