A reported robbery at a Washington restaurant last month, in which two men were alleged to have tied up and sexually assaulted patrons before making off with their jewelry, has turned out to be a “deliberate hoax” concocted in an attempt to secure immigration visas, police say.

King County Sheriff Mitzi Johanknecht says investigators are now questioning 10 people linked to the fake incident reported on Oct. 19 at Bob’s Burgers and Teriyakis in SeaTac, where officers raced after receiving a 911 call claiming “patrons were allegedly tied up, robbed of jewelry and two female members were said to be sexually assaulted.”

“I can confirm to you that it was all a lie,” Johanknecht revealed at a press conference Monday. “Every employee present that evening, every customer participated in a deliberate hoax.”

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Johanknecht said detectives believe the participants orchestrated the hoax because they wanted to apply for “non-immigrant U visas,” which “are available to those who are victims of crime and have suffered substantial mental or physical abuse and who assist law enforcement in solving that crime.”

She added: “Our detectives believed that participants hoped to avoid deportation [by] applying for and receiving a federal U visa."

The immigration status of the 10 alleged to have been behind the hoax is not immediately clear.

Johanknecht said the robbers were described as two Samoan males who escaped in a brown pickup truck that belonged to one of the victims.

But “fairly early in the investigation,” she said, “there were several things that were not making sense.”

“Eventually somebody offered up the true and correct information and then that, of course, made somebody else say, ‘yea, we made it up’,” Johanknecht added.

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SeaTac Police Capt. Jon Mattsen said Monday that the hoax consumed a “tremendous amount of resources” from his department: nine deputies and a sergeant who initially responded to the scene, and another six detectives who continued working on the case.

“For this elaborate of a hoax to have occurred, and for this many people to have undertaken this event, it shows that there was a lot of planning involved in this, and that there was a lot of active thought put into how this was going to be undertaken,” he said.

“I don’t recall a time where I’ve seen 10 people band together to form a story and present it to individuals whose very job is to note consistencies and inconsistencies… to flesh out the truth,” Mattsen added. “Never seen this happen in 30 years.”

The reported robbery generated an outpouring of support from customers and the community in the days and weeks afterward, KOMO News reported.

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Yet now, Johanknecht said, police, detectives and prosecutors are deciding what charges may be filed against the participants at the state level. As of Tuesday, police have not taken anyone into custody.

“This hoax should be an affront to all of us – especially those real victims of violence and sexual assault that U visas were intended to protect,” she said.