The FBI has announced that a letter addressed to the White House has been quarantined after testing positive for the poison ricin. The agency said Wednesday evening that it had a suspect in custody.

Federal agents have arrested a man they believe mailed the letters to President Obama and Senator Roger Wicker that “preliminarily tested positive” for the poison ricin.

The FBI named a Paul Kevin Curtis of Corinth, Mississippi as its arrest.

Although the letter initially tested positive for the deadly poison, official test results will be available in 24 to 48 hours. According to a law enforcement official, preliminary tests are "unreliable" and often result in false positives.

In an intelligence bulletin obtained by AP, the FBI says that both letters say: "To see a wrong and not expose it, is to become a silent partner to its continuance." Both are signed, "I am KC and I approve this message."

Federal officials said at that time that they believed they knew who sent the letters.

Information regarding the suspect, Paul Kevin Curtis, has since emerged via online profiles and YouTube. Evidently, 45-year-old Curtis is a father of four, an Elvis impersonator, a self-proclaimed member of Mensa and a martial artist.

According to Prentiss County Sheriff, Curtis, who suffers from severe psychological issues, has been arrested four times before, once for stalking. His LinkedIn profile currently has a long list of seemingly unrelated professions, spanning everything from “reflexology massage therapist” to “Guiness World Record recipient” and “published song writer.”

According to his Twitter feed, Curtis attempted to contact Huffington Post reporter Radley Balko in December of 2011 with claims that he was being targeted due to alleged whistleblowing activities.

Meanwhile, "A letter addressed to the president was received at a remote screening facility containing a suspicious substance. We are working closely with Capitol Police and the FBI in this investigation," a Secret Service spokesman said in a statement.

The letter, which was received at an off-site location away from the White House on Tuesday, is currently under investigation after being intercepted at a postal screening center.

"This facility routinely identifies letters or parcels that require secondary screening or scientific testing before delivery," White House spokesman Edwin Donovan said in a statement.

Paul Kevin Curtis. Image from Facebook page Kevin Curtis Live Fan Page

It arrived the same day as an envelope addressed to US Senator Roger Wicker, which tested positive for ricin. The envelope was postmarked Memphis, Tennessee and did not have a return address. The newest letter is believed to be from the same sender..

Arizona Senator Jeff Flake also received two suspicious letters at his Phoenix office on Wednesday. He later confirmed that no dangerous materials were found inside the envelopes.

Michigan Senator Carl Levin and Alabama Senator Richard Shelby reportedly received suspicious letters, as well.

Officials talk outside a mail sorting facility April 16, 2013 in Hyattsville, Maryland (AFP Photo / Drew Angerer)

The entrance to the office of U.S. Senator Roger Wicker's (R-MS) is shown in the Dirksen Senate Office Building on Capitol Hill April 16, 2013 in Washington DC (AFP Photo / Drew Angerer)

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