The suspicion is based on letters sent to the media, among other things, with confessions and detailed descriptions of some of the sabotage, said Herbert Reul, Interior Minister of the federal state of North Rhine-Westphalia, at a press conference.
In addition, suspected explosives were found at the home of the 48-year-old suspect, Reul added.
"We must assume that this is a case of climate extremism," said German Interior Minister Alexander Dobrindt at the press conference.
The author of the letters is said to have cited the fight against fossil fuels as his motive.
Recent events
The German electricity grid has been hit by several acts of sabotage and suspected sabotage attempts this week, where cables were placed on top of power lines, ostensibly to cause a short circuit and affect the electricity supply to nearby coal-fired power plants.
In the last 24 hours, two new suspicious incidents have been reported.
Early on Friday, police were called to a transformer station in Ganderkesee near Bremen in the state of Lower Saxony. The station was cordoned off, but according to police there was no danger to the public.
Homemade rockets
Hours earlier, late on Thursday, passersby discovered objects at a substation in Dormagen between Cologne and Düsseldorf, reports Westdeutscher Rundfunk (WDR).
So far, no damage has been caused. It is also unclear whether this had the capacity to cause any damage, police spokesperson Claudia Suthor told WDR.
According to German media, it involved some type of launch or firing device for homemade rockets, as well as timers and copper wire. A spokesman for the Cologne police told Bild that “someone has deliberately tried to cause a short circuit.” The whole thing is reportedly being investigated as suspected sabotage.
