Mixing past with present tense

Hello Friends,

I want to know if all three sentences are right.

#1 James was as sadistic as a serial killer who tortured his own mother (past tense throughout).

#2 James was as sadistic as the serial killer who tortured his own mother (same as above but THE serial killer instead of a serial killer).

#3 James was as sadistic as a serial killer who tortures his own mother (past tense and present tense mix).

Are all three right? While writing in past tense, should the comparison also be in past tense (tortured instead of tortures in this case) for consistency? Or is it okay to mix past with present tense in these instances?

Thanks so much,

Annie