I'd do extremely slow painful torture.
Imagine one of those 500 same knifes you have in your kitchen. They're not good but they do the job. Now, i'd start from the shoulders, and slowly move down with the knife, but as i reach the feet, i'd put more force on the knife to actually cut his skin. Not to the point that it bleeds(Only a little), but till the point that you know he's feeling pain.
If it doesn't work, go deeper.
After that, get a hammer, and bash his kneecaps.
Then get a screwdriver, small tip for it.
Drill into his stomach.
10 times.
then some other messed up stuff.