Rivera, 33, was boating with her 4-year-old son Josey Wednesday when she vanished.
The child was wearing a life jacket when he was discovered, alone and sleeping, on the boat.
Search parties have been looking for Rivera since.
Officials said Thursday that they were treating the search as a recovery mission not a rescue and the actress is presumed to be dead.
A representative for the Ventura County Sheriff’s Office told ETOnline that Rivera’s relatives were with investigators Saturday at Lake Piru.
ABC producer Anastasia Williams posted a photo on Twitter Saturday captioned: “The search continues for Naya Rivera. @VENTURASHERIFF told press that this man and woman are Naya’s mother and brother. Her mother is kneeling on the dock with her arms outstretched towards the water.”
“Naya’s mother and brother have been at the lake every day since Naya disappeared. They have been in constant contact with the Sheriff’s Office and involved in the search. On Saturday morning, they joined the search on a sheriff’s boat,” an unnamed source told People.com.
TMZ said Rivera’s father and her ex-husband, Ryan Dorsey, were also at the lake Saturday.
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