MILLBRAE, Calif. (KGO) -- San Mateo County Sheriff's detectives are using cellphone pings to retrace the steps of a missing man.
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Keith Green, 27, left his wallet and car behind when he left his home in Millbrae on Thursday evening.
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A friend said Green was going to meet with his ex-girlfriend about a child custody issue.
A hiker found Green's cellphone in San Francisco's Golden Gate Park on Friday.
His family and friends are planning to hold a candlelight vigil on Thursday night, hoping for his safe return.
It's set for 7:30 p.m. at Green Hills Park in Millbrae.
Click here for full coverage on the investigation into the death of Millbrae father Keith Green.
Detectives using cellphone pings in search for missing Millbrae man