the man who has been arrested is a man named paul kenneth curtis. joining me is washington post reporter ed o'keefe. what can you tell me about the arrest investigation in d.c.? >> we know an arrest was made today. and the fact that this happened so quickly, we seem to get a sense yesterday they were moving in on someone because senators who were briefed on this yesterday afternoon were told that the suspect they believed had done this was someone who had written to government officials in the past. having tracked suspicious mail cases for a few years, i can tell you there are several different people out there that the u.s. postal investigation, the fbi and the police track on a basis. they can track the handwriting, the style of writing and the materials sent. in this case they were able to move quickly and find this guy, paul kenneth curtis, who lived in this mississippi area. >> we talked to the people down there and they tell us he's an elvis impersonator. his facebook page says he's a self-proclaimed mensa expert. he has a beef with washington

the suspect is identified as paul kenneth curtis. for more we go live to washington d.c. the very latest with mike. >> sean, good evening. fbi announced an arrest in this case this evening. today at approximately 5:00 p.m. special time special agents arrested paul kevin curtis, the individual believed to be responsible for the mailings of the three letters sent through the u.s. postal inspection service which contained a granular substance that preliminarily tested positive for ricin. the letters were addressed to president obama, senator rodger wicker and a judge in that state. they are likely sent from a writer who is a frequent writer to federal officials. two letters were quite similar. both letters determined to be similar based on targets, post marks and et cetera. both are postmarked out of memphis, tennessee on april 8, 2013. both letters signed, quote, i am k. c. and i approve this message." at the white house here is jay carney's take. >> there was a letter. the off-site facility feeted a suspicious substance and a test was undertaken. the fbi has the lead this