He has since been released on grounds there was not sufficient reason to hold him in detention pending the outcome of the investigation, said Georg Ungefuk, a prosecutor with the Frankfurt-based office responsible for cybercrimes, which is carrying out the investigation.

Germany’s main government network was breached by hackers in 2015, and the authorities worried that information obtained then would be used against politicians leading up to the 2017 election. Those fears were largely unfounded, but Mr. Seehofer, the interior minister, warned that last month’s breach should be a warning to everyone, especially ahead of the European parliamentary election in May.

“We must be prepared that outside actors may want to influence this election and take every precaution to prevent this and do what we can to recognize such an action as early as possible,” he said. “It could be a very different perpetrator.”

Despite the shock that a single person was able to agitate and alarm the country’s political establishment, Mr. Münch pointed out that many young people had committed crimes from computers in their bedrooms, citing examples of teens who had been caught selling weapons or drugs over the “dark web,” areas of the internet hidden from the view of most users.

Dirk Engling, spokesman for the Chaos Computer Club, a German collective of hackers, said the hack itself wasn’t technically difficult, but required a great deal of patience in order to learn the necessary passwords.

He listed previous examples in Germany of such hacks where an individual’s private information was stolen for the purposes of publishing online, known in the tech world as “doxxing,” but pointed out that they had largely gone ignored by policymakers.

“Now that they have been snatched from their online accounts, suddenly it seems to have changed some minds,” Mr. Engling said.