According to Nico, Arno was a pharmaceutical baron who created amphetamines during post-war slimming and diet boom. He was also a millionaire and gave donations to several charities like in the orphanage where he grew up.
Nico learned about Arno when she started to investigate about the costume killer. Together with Yamada, Arno ended up being one of Khan's victims. Arno was killed in his house by a costume killer dressed as a snowman. His death was witnessed by his Filipino au pair. In his will, Arno has no living relatives and he gave his money to the orphanage where he grew up.
It is revealed in Imelda Carchon's secret message that Arno and Yamada visited Paris in the second week of July at the same time and implied that they were the members of Neo-Templars. Imelda warns Plantard that they're becoming the assassin's next target.
Arno is a Germanic name meaning "strong as eagle". His surname Bilotta came from the Old French word bilotte meaning a ball game using small balls.