A former member of the Navy was taken into custody in Utah on Wednesday on suspicion of mailing envelopes filled with a suspicious substance to top federal officials, including President Trump.

The man, identified as William Clyde Allen III, 39, was taken into custody in Logan, about 85 miles north of Salt Lake City, according to local FBI spokesman Doug Davis.

“No wider threat to the public safety exists at this time,” Davis told the Logan Herald Journal. “As it is a pending matter, that’s all we can say at this time.”

Two envelopes sent to the Pentagon, one addressed to Defense Secretary James Mattis and the other to Chief of Naval Operations Adm. John Richardson, contained a return address that linked them to the former sailor, officials told Fox News.

Meanwhile, Pentagon spokeswoman Dana White told reporters traveling in Brussels with Mattis that the substance sent to the Pentagon was castor seeds, not the deadly poison ricin, as originally suspected.

Ricin is part of the waste “mash” created when castor oil is produced.

If it is made into a partially purified material or refined, ricin can be deadly, according to the Centers for Disease Control and Prevention.

Another envelope was addressed to Trump at the White House.

A tip from the White House led officials at the Pentagon to discover the envelopes sent there.

They were delivered Monday to an off-site mailing facility.

The Secret Service revealed late Tuesday that it had received a “suspicious envelope” addressed to the president the day before.

The agency said the envelope “was not received at the White House, nor did it ever enter the White House,” adding that the agency was “working jointly with our law enforcement partners to fully investigate this matter.”

A fourth envelope was sent to Sen. Ted Cruz’s Houston office.

With wires