Washington CNN  — 

An employee of the drug recovery center that Vice President Mike Pence abruptly withdrew from visiting agreed to plead guilty last week to federal drug trafficking charges.

Jeff Hatch, who is listed as the chief business development officer at Granite State Recovery Centers, is accused of moving 1,500 grams of fentanyl, an extremely potent synthetic opioid, from Massachusetts to New Hampshire, where he then handed some of it off to an alleged area drug dealer, according to a plea agreement.

Two people familiar with Pence’s cancellation said the reason for the sudden decision – which went unexplained for weeks – was a federal law enforcement investigation.

It was unclear whether Hatch was the sole reason for the cancellation. The vice president’s office declined to comment on Hatch.

But a person familiar with the matter said Pence was never scheduled to interact with him during his planned visit to Granite Recovery Center in Salem, New Hampshire.

Politico first reported on Hatch’s plea agreement.

At the time, the White House refused to explain Pence’s cancellation. One person familiar with the cancellation described it as a site issue, but didn’t specify what the issue was. Another said there was a problem surrounding the event and clearing one or more of the people involved.

Local and federal law enforcement officials said after the event was canceled that there had not been a reported security incident.

Later, Trump described the reason for the cancellation as “very interesting” but also declined to specify the reason.

The abrupt change prompted a last-minute scramble – and caused complaints among staffers about how the situation was handled.

As Air Force Two was idling on the tarmac with staff and the vice president on board, the trip was suddenly scrapped, though aides back at the White House weren’t immediately informed.

Instead, reporters found out after the volunteer staffer in Salem, New Hampshire – where the Granite Recovery Center is located – announced the vice president wouldn’t be coming after all.

“We’ll just ask that you all calmly go ahead and have all of you leave the room,” the staffer told the crowd, according to video posted online.

Canceling a trip moments before a presidential aircraft is scheduled to depart is rare. It was so unexpected that Secret Service agents had to scramble to send Pence’s motorcade to the airport so he could get to the White House.

As they tried to contain the panic, people close to the vice president initially said it was a personal matter, though an official said later that it wasn’t. But it set off a furor in the West Wing, because aides there also were not informed what caused the cancellation yet were faced with questions from reporters.

Aides later conceded the matter had been handled poorly, but still refused to offer a reason for the scramble.