Thomas Cox made money selling his 16-year old victim.
Now, he's looking at up to 24 years in federal prison.
Cox, 27, of Buffalo, admitted Monday to coercing an underage girl into prostitution and then taking the money she earned from customers here and across the country.
"They were advertised on backpage.com and advised to walk the streets," Assistant U.S. Attorney John Fabian said of the minor girl and two other alleged victims.
Cox pleaded guilty to sex trafficking a minor and, because of a previous criminal record, will face a recommended sentence of up to more than two decades in prison when he is sentenced by U.S. District Judge Richard J. Arcara.
His conviction was the result of an FBI investigation.