The German football association (DFB) has opened investigations against Hoffenheim and Borussia Dortmund following incidents that occurred before the teams' 1-1 draw on Saturday.
Hoffenheim owner Dietmar Hopp was verbally abused by some travelling Borussia Dortmund fans who displayed several offensive banners, including one showing a portrait of the 78-year-old in crosshairs with "Hasta La Vista Hopp!" written underneath.
The banners were a reply to a banning order sent last week to at least 33 Dortmund fans who insulted Hopp in May during the final match of last season.
"The DFB control body has opened proceedings against TSG Hoffenheim (suspicion of insufficient security) and Borussia Dortmund (unsporting behaviour of its fans)," the DFB said in a statement released to ESPN FC.
There were also reports that Dortmund supporters destroyed some restrooms at the Wirsol Rhein-Neckar-Arena in Sinsheim.
While Dortmund must explain their fans' behaviour and could face punishment of a partial stadium ban or a closed away end when they next travel to Hoffenheim, the hosts must answer why Dortmund supporters were able to smuggle the giant banners into the block.
Dortmund fans attending the match told ESPN FC that security had been tight, with officers searching the purses of those sitting in the away end.
In an open letter published on Hoffenheim's website on Sunday, they called the banner an "incitement to murder" and said they are "deeply shocked by the insults against Dietmar Hopp."
Christoph Schickhardt, the lawyer representing both Hopp and the club, told SWR that "in the future, a game should not be kicked off like that."
Dortmund CEO Hans-Joachim Watzke apologised to Hopp in a statement posted on the club's website.
"We tried to de-escalate last week as things were blowing up," Watzke's statement read. "We talked to all parties, but sadly, we were not successful. Such a behaviour in no way corresponds with the values of Borussia Dortmund."
It had not been the first time the crosshairs were on display at a Dortmund match in Hoffenheim.
When the sides met for the first time in the Bundesliga in September 2008, a smaller version of the banner was displayed as Dortmund supporters began their protest against Hoffenheim under the slogan, "Tradition beats every trend."
That day, Hoffenheim fans replied with: "Tradition beats every trend. We are not a trend. We are the future."
The relationship between Hopp and Dortmund supporters has been strained since 2008, when Hoffenheim were first promoted to the Bundesliga behind financing from Hopp, a local billionaire. In 2015, Hopp was allowed to take over his hometown club after 20 years of funding it.
While most of the animosity was initiated by the Dortmund fans, in 2011, Hoffenheim admitted to having used a sound system to fill the away stands with loud and strident noise. They argued that the stadium's caretaker had installed the sound system without the club's approval.
Dortmund supporters and other fan groups in Germany believe Hoffenheim's arrival opened the door to the undermining of the Bundesliga's football culture by working around the 50+1 rule, which stipulates that more than 50 percent of a club must be owned by its members.