1996 Dodge Avenger

1996 Dodge Avenger ES, v6, automatic. Recently, brake lights won't turn off even when the car is off and keys out of ignition. We have replaced the switch at the brake pedal, and it worked perfect (that is that the brake lights turned off when car was off), however the next morning our car was dead.
We suspect this switch is draining our battery (because the battery is brand new), but we don't know where to look in the wiring. Would it even be in the wiring? We have replaced all three relays under the hood on the firewall in 2011.
For now, we have no brake lights again (because we unplugged the switch so the car won't be dead when we go to leave), but we do have all other lights such as reverse, running, parking, and turn signals(no interior though). Please help us find the source.
September 17, 2012.

The switch cannot be bad if the lights work correctly.

Was the switch adjusted correctly?

Reconnect the switch and note if the lights stay on. If it is not adjusted correctly, it might light up with minimal movement of the brake pedal.

Sep 17, 2012.
The first switch was bad, because the tail lights stayed on even when the car & lights were off. The second switch worked perfectly fine and was correctly adjusted; it's just when we turn the car off (with the new switch still in) after a few hours the battery will be completely dead even though the lights are not on. Which is why we think it must be in the wiring related with that switch possibly.

Sep 21, 2012.
The switch itself is straight forward, if it is faulty, it can either be no lights or lights stays on all the time. If battery is drained without the lights turning on, it cannot be the switch that is causing it.

You would need to check the turn signal and hazard flasher unit, to which the brakes are linked to, except the third brake light.

Sep 21, 2012.