A hacker broke into T-Mobile’s mobile data network, accessing the e-mail and files of hundreds of customers, including those of the secret service agent investigating the crime, according to wire reports today.

Nicolas Lee Jacobsen, 21, was charged for the computer crimes in Los Angeles U.S. District Court. Investigators traced Jacobsen to a hotel he was staying at near Buffalo, N.Y.

According to court records obtained by news outlets, between March and October Jacobsen allegedly accessed the accounts of 400 customers, viewing Social Security Numbers, birth dates and passwords, information which he later used to access their e-mail accounts online. T-Mobile said that the affected customers have all been notified, and the hacker had no access to credit card numbers or any financial information.

The Secret Service investigator, Peter Cavicchia, specialized in tracking hackers. He was also coincidentally a T-Mobile customer and used a T-Mobile handset to access government files.