Security footage has been released showing the last known movements of Glee actor, Naya Rivera, who is feared to have drowned after taking her four-year-old son out on a lake in southern California.

The CCTV video was made public by law enforcement after an extensive search of the area, which reportedly involved dive teams and helicopters, failed to locate the 33-year-old, who is presumed to be dead.

The footage shows Rivera arriving at the lake in her black 4x4, and taking her son from the back seat before walking over to the pontoon. It also shows her boat leaving the dock and heading out onto the lake.

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The Glee star - who played cheerleader Santana Lopez in the hit musical TV show - had reportedly rented a pontoon boat on Wednesday afternoon, but just three hours later, another boater raised the alarm after finding Rivera's boat with just her son asleep inside, BBC News reports.

Police did find Rivera's life vest in the boat and believe that "she did go in the lake" for a swim.

Officials from Ventura County Sheriff's office say that they acknowledge that "this may well be a case of drowning". Her car was reportedly found nearby.

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Ventura County Sheriff's Department Captain Eric Buschow told The Los Angeles Times that investigators arrived at the scene at roughly 4:40PM and found a young child "unharmed".

He added: "He's in good health. The family is going through a very traumatic time right now."

Prior to being pronounced missing, Rivera's last Instagram post sees her cuddling her son. "just the two of us," she captioned the picture.

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Another post, published six days ago, sees the 33-year-old tell her fans: "no matter the year, circumstance, or strifes everyday you're alive is a blessing. make the most of today and every day you are given. tomorrow is not promised [sic]."

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After the news broke, several of Rivera's Glee co-stars took to social media to express their concerns and prayers.

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Actress Heather Morris wrote on her Instagram stories: "We need all the prayers we can get to bring our Naya back home to us. We need your love and light."

And Harry Shum Jr. simply tweeted: "Praying."

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Rivera married fellow actor Ryan Dorsey back in 2014, and the couple welcomed their son - Josey Hollis Dorsey - in 2015.

The couple divorced in 2018, but maintain joint custody of their son.

CCTV shows Naya Rivera's last movements before disappearing