Police so far aren't talking about the case, except to say they're serving search warrants.
According to a source with knowledge of the SFPD investigation, foul play is suspected and officers have identified a person of interest in the case of missing man Piseth Chhay.
The source believes Chhay owed money to the person police think is responsible for his disappearance.
That person, Bob Tang, was supposed to talk to investigators, but he did not show, according to the source. They now think Tang may have fled to his home country of Cambodia after his wife reported him missing to police on Wednesday.
VIDEO: Police search industrial area in SF as part of missing Uber driver investigation
Police search industrial area in SF as part of missing Uber driver investigation
On Tuesday night, investigators from the Special Victims Unit served a search warrant in San Francisco's Bayview neighborhood at the Maple Trade Center on the 1200 block of Van Dyke Avenue.
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A person who answered the phone at the office said investigators provided no details.
The Maple Trade Center is about two miles from where Chhay's Mercedes was found stripped of everything, including its wheels.
The car was found last Saturday.
Chhay, the 47-year-old father of two and full-time Uber driver, disappeared the weekend before on Mother's Day. His family and friends have been scouring Bayview, looking for answers and witnesses.
The car was found abandoned near a homeless encampment. People there noticed the car, but nothing else that could help.
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"This is a dedicated family man with children and extended family," San Francisco Supervisor Asha Safai said.
Safai represents the district where Chhay and his family live and has spoken to police.
"They're in the process of doing discovery or requests to the courts to release information from phone records, and that information hasn't been provided yet. As of Monday, it has not been provided yet," he said.
"I'm sure at least one person out there saw something, so please come forward and help us find him. You know at the end of the day, that's all we want," Sovanarath Chi, Chhay's cousin, said.
Police have been tight-lipped about the case. A source with knowledge of the investigation says there will be more search warrants as they solidify leads.
Chhay disappeared on Mother's Day, while driving to a friend's house.
Chhay's family stood speechless in the spot where his silver Mercedes was dumped on Davidson Avenue.
The homeless who have tents in the area only noticed the car, but not Chhay.
"We saw it on the corner yeah, that's about it," one man said.
"If someone car jacked him, took him somewhere, dumped his body somewhere that can't be found and then take his car and dump it at another place," friend Brandan Tang said.
Investigators took Chhay's laptop, iPad, toothbrush and razor in a search of his house.
"We just have to keep the hope that he is in a good place and that he is OK. There is nothing that I can see at this point that would indicate that he is in trouble," SFPD Lieutenant Ed Santos said.
That's not what Chhay's wife of 20 years thinks. She's sure he is in trouble.
"His son is waiting for him for God's sake. His family is waiting for him. I give you anything you want. All I want, him to come back," wife Rattana Kim said. "He loves his family way too much to leave without telling us where he's going or not even a phone call."