SPOKANE, Wash. — Three medical marijuana shops in the Wenatchee area have closed down after federal prosecutors sent a letter to the businesses' landlords.

The letter sent last week by Eastern Washington U.S. Attorney Michael Ormsby threatened to seize the properties and to fine or imprison the landlords.

Medical marijuana store operator Eric Cooper says the letters prompted three existing dispensaries to close immediately. He says the fourth shop in the area is staying open a little longer but also intends to close.

"We all probably got spooked a little easier than we should have," said Cooper, who has operated a medical marijuana dispensary called Apple Capital Holistic Care since May.

But the operators did not want to face criminal records, Cooper said.

Officials with the U.S. attorney's office in Spokane did not immediately return a message seeking comment.

Cooper said he decided to close his shop immediately after his landlord received the letter.

"I would not put my landlord in that type of position," Cooper said. The letter gave landlords 30 days to evict the dispensaries.

"We ran a really nice, clean professional operation in a nice location here in Wenatchee," Cooper said. "We were doing everything by the book.

"I don't feel good," he said, adding the closing of his shop put seven people out of work.

Washington is among 16 states and the District of Columbia that have laws allowing the medical use of marijuana, and that has led to the opening of dispensaries in cities across the state. But federal law holds that marijuana use is illegal, and federal law enforcement officials have moved to shut down many of the dispensaries.

An initiative to legalize and tax marijuana in Washington state is on the November ballot.

Initiative 502 would legalize possession and sale of up to 1 ounce of marijuana. It also would impose a steep excise tax on marijuana and cannabis-infused products at new state-licensed marijuana stores, and would allow state-regulated grow farms.