I saw someone suspicious.
sos-PET-toh — double 't' creates a brief stop; stress on the second syllable.
Use when reporting suspicious behaviour that may not yet be a crime. Italian police take such reports seriously and can dispatch a patrol to investigate.
'Sospetto' functions as both a noun (a suspect) and an adjective (suspicious). When used as an adjective after a pronoun, it follows 'qualcuno di + adjective' — the 'di' is required.
C'è qualcuno che si comporta in modo strano.
There is someone behaving strangely.
Describes behaviour rather than appearance.
Ho notato un'attività sospetta.
I noticed suspicious activity.
More formal — used for reporting a general situation rather than one person.
Un uomo sta girando intorno alle macchine parcheggiate.
A man is circling around parked cars.
Specific description — most useful for police dispatch.
The term 'volante' refers to a fast-response police patrol car — recognisable by the blue livery and 'POLIZIA' markings.