2000 Suburban Horn Doesn't Work

I just bought a 2000 Chevy Suburban 5.3L and the horn doesn't work. It used to be a police vehicle so I guess they disconnected the horn. I checked the horns and they are there and connected. I also checked the fuses and the electrical center and everything is also fine there. Anyone familiar with where they disconnect horns on police cars or have any ideas where else I should check? Thanks.