A Utah man who sent powder-filled envelopes to politicians is a Navy veteran who has spent years posting pseudo-scientific and anti-government conspiracies to Facebook.

William Allen III, 39, confessed Wednesday to sending envelopes full of ground castor seeds to President Donald Trump and high-profile members of the Trump administration. The envelopes were initially believed to contain ricin, a highly lethal poison that can be produced from the less-toxic castor seeds. Authorities traced the powder-filled envelopes back to his home after they discovered his return address on one of them, according to a charging document.

Authorities have not announced a motive for the attacks. But Allen’s Facebook posts indicate interest in anti-government conspiracy theories about government mind control and half-baked science advice, including recipes for extracting poison from seeds.

Allen, a former Navy sailor is accused of sending the envelopes to Trump, FBI Director Christopher Wray, Defense Secretary James Mattis, and Chief of Naval Operations Admiral John Richardson on September 24. Senator Ted Cruz also received a powder-filled letter that day, although officials have not implicated Allen in that incident.

The envelopes contained crushed castor seeds, which are toxic if ingested, but not nearly as poisonous as ricin, a small amount of which can be lethal. Castor seeds can be used to make ricin, but the process is more complicated than crushing the seeds.

After Trump administration officials received the powered substance, observers speculated that a left-wing opponent might have sent the envelopes. Allen’s social media history suggests a less partisan attack. Though public records show Allen to be a registered Republican, he spent years sharing broadly anti-government posts, particularly in relation to the FBI and CIA.

The posts were often unintelligible, detailing pseudo-scientific concepts, religious passages, or devices that could facilitate mind control. In December, Allen shared a video about “extracting cyanide from apple seeds with hydraulic press.” Allen also occasionally commented on medical institutions’ or politicians’ Facebook posts. He spammed two cancer foundations with posts in December, claiming to know the cure to cancer.

Last year, he commented on a post by George W. Bush’s secretary of defense Donald Rumsfeld, extremism researcher JJ MacNab noted on Twitter. In the semi-legible comment appeared to offer a pseudo-scientific alternative to torture.

Allen served in low-level U.S. Navy roles from 1998 to 2002, Newsweek previously reported. Two years after leaving the Navy, he was charged with child sex abuse against two girls with whom he had a “relationship of trust,” the Associated Press reported. He pleaded guilty to reduced counts of neglect and abuse. AP also reported that a woman successfully obtained a protective order against him in another case, and that in 2008 he pleaded guilty to attempted aggravated assault.

Allen’s Facebook posts have previously landed him in headlines. The public-shaming blog Counter Domestic Terrorism accused Allen in December of harassing a female veteran by posting her home address and military records.