A copy of Adolf Hitler's book Mein Kampf has been found in the house of a man thought to have shot six black migrants in the Italian city of Macerata.
reports that Luca Traini is being held on suspicion of attempted murder with an aggravating circumstance of racial hatred for allegedly targeting the five men and one woman in drive-by shootings on Saturday.
Video of the suspect's bedroom released by police on Sunday showed Hitler's autobiography and other publications linked to Nazism.
Traini, 28, had an Italian flag draped over his shoulders when he was arrested and witnesses said he had also made a fascist salute.
The six injured were aged between 22 and 33 and originally from Ghana, Gambia, Nigeria and Mali, according to Italian broadcaster RAI.
Police commander Michele Roberti told Sky TG24
that the shooter was "lucid and determined, aware of what he had done".
Roberti added: "It's likely that he carried out this crazy gesture as a sort of retaliation, a sort of vendetta."
The shooting happened just days after a Nigerian man was arrested in connection with the death of an 18-year-old Italian woman.
Pamela Mastropietro's body was found dismembered and packed into two suitcases near Macerata.
Just after Saturday's shooting spree, Times journalist Tom Kington had told Sky News that Ms Mastropietro's murder had "created a huge wave of intolerance towards migrants locally, and has also been picked up by national right-wing politicians".
Immigration has become a key issue in the national election, which is set for 4 March.
More than 600,000 migrants - mainly from Africa - have reached Italy by boat over the past four years.
Matteo Salvini, head of the anti-migrant Northern League, has capitalised on Ms Mastropietro's murder in his campaign, and has vowed to deport 150,000 migrants in his first year of office if elected.
It has emerged that Traini once stood as a candidate for the right-wing party at last year's local elections but he did not receive any votes.
Meanwhile, Italy's prime minister said the country will not be divided by "hatred and violence".
PM Paolo Gentiloni warned: "The state will be particularly severe towards anyone thinking of fuelling a spiral of violence.
"Let's stop this risk, let's stop it right away, let's stop it together.