Carmen is Captain Stanton Gerrard, a tough cop who takes no guff. (Direct quote from the CSI: NY website.) There's a lot of yelling involved as Stella and Mac are trying to defend their colleague while poor Captain Gerrard is trying to run a murder investigation. Yeah, so Carmen yells a lot, gets to use a crowbar (yeah, every NYC PD department has a crowbar handy) and shakes his finger of doom also.