Micah Johnson, the man who killed five police officers in Dallas last week and injured seven other people, allegedly bought an AK-47 assault rifle over Facebook in 2014.  

The man who sold Johnson the gun, Colton Crews, Told the New York Daily News that nothing seemed off about the future killer. (It’s also worth noting that gun sales weren’t outlawed on Facebook until this year.)

“He didn’t stand out as a nut job. He didn’t stand out as a crazy person at all,” Crews said. “He stood out as just another guy. And he was U.S. service, so he was like your first pick when you’re selling a gun to somebody.”

It isn’t believed Johnson used the AK-47 in the Dallas ambush, but the revelation that such a heavy assault weapon could be so easily purchased on Facebook has caused the site’s critics to take note. U.S. Senator Edward J. Markey wrote a letter to Instagram and Facebook this week calling on the sites to prohibit gun sales.

“As recently as today, my office was able to find postings for gun sales on Facebook using search terms like ‘AR15 Selling’ and ‘selling sig sauer,’ and on Instagram using search terms like ‘#Glock’ and ‘#PistolSale,’” the senator wrote.

Both sites technically already have rules against the private sale of firearms. However, there’s no doubt they need to step up their efforts to stop all sales from taking place — not just most of them.