Oh... and as a "humane" way of catching mice... I'd suggest investing in a humane "live" trap such as the "tin cat" or have-a-hart catch and release traps. There are a variety of other humane traps available ranging in price from around $5 - $25 that are good.
When you place a trap, put it in a room where you have seen a lot of mouse traffic. Place a small amount of food, pretty much anything would be good though I have heard of people having success with a few kibbles of dog food, inside the trap. Place the trap against a wall, under a piece of furniture usually works good. Make sure it's fairly easy to access without disturbing things too much and check it once daily... It might take a few weeks before you start catching any mice, but I think that might be because there is no "mousie" type smell to the trap and the smell of humans might be strong for the first little bit. But give it some time and you should start catching lots of mice.
BTW... if you decide to release them again... make sure you take them at LEAST 3 miles away from your home or they will make their way back.
Good luck!!
Annie B.