The strange man has a stubble and wears dark sunglasses. He also wears a fedora and a trench coat. He has a scar running down his left cheek.
He appears to you, seemingly warning you that the Scream will be stolen. This is actually part of the Black Widow's plot. He frames you for stealing the painting before swiping it while the police were occupied with you. He formerly worked for the Black Widow, but he quits after she double-crosses him. After that, he's on your side (to prove it, he helps you escape and take the Black Widow to justice). After this, it is unknown what happened to him.