Smoke odor in carpet.

[Mark Forest]

The prior owners in my rental property must have been smokers. We have cleaned, primed, and painted the walls, cabinets etc. However we still smell cigarette smoke, so it must be in the carpet. We have steam cleaned the carpet several times, but the odor remains. There must be a chemical out there that will take care of this. What do you all use? Thank you in advance to all who help.