He returned home and shared this wonderful news with his 2 roommates.
On Monday Mr Saosongyang was "invited" to come collect his stolen winnings, investigators say, "but instead of him celebrating his big win he was arrested".
Suspecting one of his roommates of stealing the real ticket and replacing it with a fraudulent one, he reported it to the police department.
Police also have a video of 35-year-old Adul Saosongyang, the victim's roommate, going into the store hours later to buy a ticket.
Saosongyang was not able to immediately walk away with the prize money.
But when he attempted to collect his winnings the following morning, he was told his ticket wasn't a victor and had been altered.More news: British PM Theresa May loses key vote on Brexit procedure in parliament
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The following day, the man's roommate, Adul Saosongyang, 35, attempted to turn in the real winning ticket and was informed that the ticket was actually worth $10 million.
Upon visiting the store, they learned the ticket had been reported stolen.
At this point the Lottery authority was unaware of any nefarious activity and began the usual administrative investigation it does into any large winnings, telling Saosangyang to return to collect his money on January 7.
The Lottery investigator began comparing notes with a Vacaville PD detective on the suspected theft.
An investigator lured Saosongyang to the district office by telling him he'd pick up the cash, only to be swiftly arrested by police. Collecting a prize of such a sum involves submitting a detailed claim form, either in person at a district office or else in the mail, according to the state lottery. He had purchased a similar scratch card, and then swapped it out for the winning ticket while his unsuspecting roommate was sleeping.
Saosongyang was charged with grand theft and is being held at the Sacramento County Jail.
"Although, I'm sure everything will work out in the end", he told the newspaper.