PORTLAND, Ore. — They took over the offices, a bunkhouse and other buildings at the Malheur National Wildlife Refuge headquarters, posted armed guards to monitor entry, and kept control for 41 days in a takeover that federal officials say cost taxpayers $4.3 million.

So how did a 12-person jury reach its startling verdict Thursday in U.S. District Court that cleared Ammon Bundy and six other high-profile occupation participants of a key conspiracy count?

One juror offered an explanation: The prosecutors did not make a convincing case the defendants not only participated in the plot to take over the refuge, but did so with the intent to violate the law by using threats and intimidation to keep federal workers from their jobs.

In an email Friday to The Oregonian, a man identified as Juror 4 wrote, “We were not asked to judge on bullets and hurt feelings, rather to decide if any agreement was made with an illegal object in mind. It seemed this basic high standard of proof was lost upon the prosecution throughout.”

The Oregonian said the man is a business-administration student at Marylhurst University near Portland. Many of the other jurors were drawn from other parts of the state.

A conviction on the conspiracy count could have brought a prison sentence of up to six years.

It is one of the more serious charges that prosecutors could make against the defendants whose actions last winter helped galvanize supporters of a militant movement to challenge federal control of Western public lands. Ammon Bundy, who grew up on a Nevada ranch and faces charges over a militant protest in that state, was a leader of the occupation.