Dorsey, who was married to the former Glee star from 2014 to 2018, was spotted at Lake Piru on Sunday as authorities continue to search for Rivera.
Dorsey, 36, ventured into the water with Rivera's family, including her father George, who first arrived at the lake several days prior, as seen in a photo obtained by TMZ.
Although Dorsey has not yet made an official statement about his ex-wife's disappearance, a source told PEOPLE that Rivera's loved ones are in "disbelief."
“Nobody has heard anything," said the source. "Everybody is in a wait-and-see pattern and trying to figure out exactly what happened.”
Today's search for Naya Rivera has concluded. The operation will continue Monday morning. pic.twitter.com/YZ3TTqhOUI
— Ventura Co. Sheriff (@VENTURASHERIFF) July 13, 2020
Divers continue the search for Naya Rivera this afternoon at Lake Piru. This is day 5 of the search and recovery effort. She disappeared Wednesday afternoon while swimming in the lake. pic.twitter.com/3etxZ3ycpN
— Ventura Co. Sheriff (@VENTURASHERIFF) July 12, 2020
Authorities said Josey was "in good health" despite his mother's disappearance and was reunited with Dorsey. The toddler told investigators that his mother never got back into the boat after they had been in the water, according to a press release.
Authorities shared video footage on July 10 from their underwater search for Rivera, which highlighted the low visibility on the floor of the lake.
"Unfortunately, they did not locate Naya Rivera. They are still searching," Ventura County Sheriff's Office Captain Eric Buschow told reporters at a press conference. "We don’t know if she’s going to be found five minutes from now or five days from now."
On Saturday, a spokesperson for the Ventura County Sheriff’s Office confirmed to PEOPLE that Rivera's family members came to Lake Piru after the actress went missing.
"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," a source told PEOPLE.
On Sunday, Sgt. Shannon King confirmed to PEOPLE that investigators will be continuing to search for Rivera in the area “at least through Tuesday.”
“There’s no talk of either one way or the other after Tuesday,” King noted. “Tuesday’s sort of the projected date that we’re discussing, and we’re going to continue doing what we have been doing.”