LOS ANGELES (CBSLA) – A University of Southern California graduate student who had been missing for five days was found safe Friday, although questions remain about the circumstances of his disappearance.

Two undated photos of Bo John Jones.

Twenty-two-year-old Bo John Jones, who was studying operations research engineering at USC, had last been seen by his roommate at around 4:30 p.m. on July 8 at his downtown Los Angeles apartment, located in the 1100 block of West 6th Street. Security cameras caught Jones walking out of the complex at 5 p.m.

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His father, James Jones, told CBS2 Thursday that his son’s wallet, keys and car were left behind. His cell phone was later tracked to MacArthur Park, where it was found Tuesday near one of the playgrounds, James said.

The park is about one-mile from the apartment. James does not have the phone’s password, so he has been unable to open it.

Just after 11 a.m. Friday, James confirmed to CBS2 that his son had been found safe and unhurt. It was later learned that at about 10 p.m. Tuesday, Bo had been transported by ambulance to East LA Doctor’s Hospital, according to hospital CEO Gerald Clute.

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He was listed in stable condition Friday. The circumstances of his disappearance and where he was found were not confirmed.

“I can’t tell you what he came in under, what name,” Clute told CBS2. “But I can tell you, only today, was it absolutely revealed that this was the man who was missing. So we were able to reconnect him.”

It’s unclear how long he will remain hospitalized.

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Los Angeles police said Friday that Jones will not face charges, and no suspects are being sought.