Police in Woodbury and Oakdale are investigating an extortion letter recently sent to dozens of at-home day care operators that alleged sexual abuse of a child under their watch.

The letter, dated July 13 and written as if sent from parents, instructed day care operators to send $2,500 or face a police investigation into injuries from sexual assault allegedly found on their daughter.

Investigations Commander Steve Wills said police don’t have any legitimate reports of sexual assault at any Woodbury day care provider. He also said that no day care providers sent money in response to the letter.

The letter said: “Buying our silence will be simple and anonymous, nobody will ever know this happened. ...

“A police investigation into your day care will make other parents question the safety of your services, and likely withdraw their children, assuming of course that the findings of the police investigation don’t shut down your day care entirely.”

In Woodbury, 27 providers received an identical letter that they “recognized as a scam and didn’t fall victim to,” Wills said.

“In general we see a lot of scams. This is a new approach but the end goal is the same, trying to get money that’s not theirs.”

Letters were processed through the U.S. Postal Service distribution center in St. Paul and possibly mailed in the east metro area, Wills said.

The letter writer asked for payment in Bitcoin, a currency that allows anonymous transactions and is often used in black market trading.

“There’s no need to visit us at the return address on the envelope,” the letter said. “It’s fake!”

In Oakdale, police received 14 complaints about a letter sent to day care providers in that city, said spokeswoman Michelle Stark.

Attempted scams in Oakdale have become frequent enough that police mailed a “Don’t Get Hooked” booklet to residents and businesses about a month ago to help them detect trouble.

In one instance, Stark said, a booklet supplied to a grocery store stopped a woman from wiring $1,600 to a “grandson” who was instead a scammer.

“These scammers are truly unscrupulous,” she said.

Washington County Sheriff Dan Starry said it appears no other cities or townships received the threatening letter.