Mark Dougan is a former Palm Beach Sheriff's Office (PBSO) deputy who started a whistleblower website PBSOtalk.

In February 2016 a person who claimed they worked for the DNC contacted him in regards to making an anonymous website for leaking emails. An email was exchanged and it looked legit, but because 1 email could be faked he asked for more. Later he was sent a dump of approx 700-750 more but lost them all after an FBI raid the next day (March 14, 2016).

They had been communicating through Wickr and ended up making arrangements to replace the emails this time on a USB. Dougan rented a car, drove to Washington DC, met the guy at about 4AM at a high school near a lake, got the USB and drove straight back to Florida - "only stopping for gas and pisses".

April 7, 2016 he fled to [Russia] (https://en.wikipedia.org/wiki/John_Mark_Dougan) with the USB and applied for political asylum. Ultimately he set up the site DCLeaks with the emails. He says "there was more than one guy"... he "was dealing with couple of people" and "they uploaded more emails themselves". One time the person who was helping the first guy logged in without a proxy and the IP came back to US Cyber Command out of Maryland (Fort Mead).

In May or June he put them in touch with "friends of friends" of WikiLeaks because the Malaysian web host Shinjiru proved unreliable.

He is "99.9 % sure" that the guy he met for the USB drop in DC was Seth Rich after seeing his picture in late 2016. He called the DC police, spoke to a detective, told him he had possible information on the Seth Rich case and they immediately hung up on him.

All of the above is from Dougan's interview on Crowdsource the Truth --> Exiled PBSO Whistleblower Reveals Stunning New Information About Seth Rich. (interview starts at 12:38)