The far-right party tried to distance itself from the attacker while tweeting a link to his manifesto.
An attempt by German far-right party Alternative for Germany (AfD) to distance itself from the ideas of the Hanau attacker has backfired.
The party wrote on its official Twitter account that critics were exploiting the situation in making a link between the crime and the politics of AfD.
But in the same tweet, it included a web link to the attacker's alleged manifesto, which was intended as a "message to the entire German people".
The 43-year-old German man shot and killed nine people at several locations in Hanau near Frankfurt overnight in attacks that appear to have been motivated by far-right beliefs, according to officials.
He was later found dead near the body of his 72-year-old mother, said Peter Beuth, the interior minister for the state of Hesse.
His website is no longer available online.
'Delete the tweet!'
The AfD's tweet shocked many in Germany.
"If you don't share the same worldview as the attacker, delete the tweet and stop sharing his writings!" a Twitter user said.
In the face of criticism, the party replied again on Twitter.
"Read it. This has nothing to do with politics. He only writes about himself, his messed up life, the mind control by a secret organisation and how he came to his opinion about 'southerners' in 1999 based on his own experiences and newspaper reports."
Defence Minister Annegret Kramp-Karrenbauer told reporters on Thursday morning that the ruling centre-right CDU and all parties in Germany should not cooperate with a party that tolerates right-wing extremists and Nazis in some cases within its own ranks.
"This party is thus creating a basis for exactly the kind of thinking that led to Hanau," the politician said.
Earlier, AfD federal spokesman Jörg Meuthen wrote on Twitter that the Hanau attack was neither left-wing nor right-wing terror, but "the delusional act of a lunatic".
"Any form of political instrumentalisation of this terrible act is a cynical mistake. Instead, all the people of our country should mourn for the victims together with their families", said Meuthen.
Meanwhile, CDU MP Matthias Hauer coined the AfD as "spiritual arsonists".