Complex sentence: Suspicious, he sends his enforcer, Luca Brasi, to spy on them, but Brasi is murdered by Sollozzo, who then has Vito gunned down in the street, after which he kidnaps Hagen.
Split into simpler sentences: Suspicious, he sends his enforcer, Luca Brasi, to spy on them. Sollozzo has Vito gunned down in the street, then kidnaps Hagen.