The hacker was identified as 40-year-old Marcel Lazar Lehel, a resident of Arad, Romania, the Washington Post reported Wednesday.
Lehel gained notoriety on Feb. 7 when he broke into the email account of Bush's friends and relatives, including his sister and brother-in-law, and passed copies of dozens of emails and photos to the Smoking Gun, a website that posts incriminating public documents, mugshots and other information.
Those emails included details on former President George H.W. Bush's health problems and vacation plans, as well as artwork created by George W. Bush. The Secret Service launched an investigation into the hacking.
The hacker, who was convicted in 2012 of several other computer crimes, also broke into the email accounts of other public officials and celebrities, including Colin Powell, Clinton aide Sidney Blumenthal and "Arrested Development" star Jeffrey Tambor.
Among other officials Lehel claimed to have hacked was Romanian Intelligence Service head George-Cristian Maior. When he made that claim, Lehel said he was aware law enforcement was watching him and that he could "disappear" soon.