Could be he already was, and Cummings tipped them off. They had to have known she had the account set up. The only reason they'd 'fess up now is if they knew they were sure to get caught eventually.
There is A LOT MORE KNOWN TOO
Actually, Lerner et al did not just "fess up now." The Toby Miles email account (tobomatic@msn.com) was known to the Committee and appears in the criminal referral (april 2014)sent to the Justice Dept. where Eric Holder sat on it. http://thomas.loc.gov/cgi-bin/cpquery/?&sid=cp113DOpqK&r_n=hr414.113&hd_count=50&item=33&&sel=TOC_32811&