[Cheeba V2.0]

Saw this movie sometime in the 90's on latenight network TV.
It's not entirely horror, it's action/horror themed/crime?

Don't remember much, but here goes.
Close to the beggining, a cop and his partner (friends) enter a house on some kind of drug bust. They both seem like pretty layback kinda guys....The bust goes well, but then one of the two partners goes apeshit for no apparent reasons, and starts shooting everyone up, even the subdued/cuffed criminals. His partner ends up shooting him dead, or apparently so - and he's being investigated as a result of what went on.
Later in the plot, he sees him again or something...it's somehow revealed that he'd been experimented on with some failed ?drug or procedure?....Good cop breaks into a facility that is behind this, and is attacked by his partner, all mindlessly, who has him in a stranglehold. Somehow he manages to talk him down, and tell him what's gone on, that he's actually dead....etc, and the two of them start working together.
Anyway, I think at some point towards the end, BOTH of them end up undead. There were also other semi-zombies running around during the film, but yeah, it's all a little vague...
It was quite funny in parts...This seems weird, but for some reason I'm thinking vincent price was in it, but it was either 90's or close to it???

Anyone??