He allegedly thought he stole a $10K lotto ticket from his roommate. It was actually worth $10 million, police say

A man allegedly stole his roommate's winning scratch-off lottery ticket, and when he tried to cash in, he learned it wasn't actually worth $10,000 but rather $10 million, police say.

Adul Saosongyang, 35, was arrested Monday on charges of grand theft after police in Vacaville, California, and lottery officials began investigating the case, the Vacaville Police Department said on Facebook Tuesday.

Saosongyang's roommate purchased the scratch-off for $30 in December and thought he had won $10,000, police said. When he got home, he told his roommates then headed to the lottery office in Sacramento the next day.

There, officials told the man his ticket was not a winner and that it had been altered, police said. The man suspected a roommate and reported the theft, according to police.

"The next day his suspicions were proven true," Vacaville police wrote on Facebook.

Saosongyang allegedly went to the same lottery office to cash in on the ticket. Only, it wasn't worth the $10,000 he allegedly thought he would get – it was a $10 million ticket.

Police said lottery officials didn't know the ticket was reported stolen, and, as is standard in cases with over $600 in winnings, they began investigating.

Vacaville police lieutenant Chris Polen told USA TODAY that it was when lottery officials got in contact with the grocery store where the ticket was purchased that they were told it could be stolen.

Saosongyang and his roommate allegedly purchased their tickets at the same Lucky Grocery and surveillance video aided in the investigation, Polen said.

Police and lottery officials soon began working together. "They determined the roommate had purchased a similar Scratcher Lottery Ticket, altered it, and swapped it with the winning ticket," the department said on Facebook.

Authorities invited Saosongyang to the lottery offices to collect the winnings on Monday, police said. "Instead of him celebrating his big win he was arrested by Vacaville PD Detectives who had obtained an arrest warrant for him for Grand Theft," the department said on Facebook.

Police said he was being transferred this week from Sacramento County Jail to Solano County, and it wasn't clear if he had an attorney.

Polen said he's been on the job for 20 years and hasn't seen anything like this case. While lottery scam is not uncommon, it's "never anything of this magnitude with a $30 ticket and $10 million in winnings."

As for the $10 million in winnings, lottery officials are still working on its investigation.

"Once the Lottery verifies the identity of the winner of the ticket it will pay that claimant the $10 million prize," the California Lottery said in a statement to USA TODAY.