Ellen Nakashima reports for the WaPo:

Russian government hackers penetrated the computer network of the Democratic National Committee and gained access to the entire database of opposition research on GOP presidential candidate Donald Trump, according to committee officials and security experts who responded to the breach.

The intruders so thoroughly compromised the DNC's system that they also were able to read all email and chat traffic, said DNC officials and the security experts.

Hacking is a federal crime, but I doubt the feds are going to prosecute the government of Russia.