Attractive as it may seem to eliminate people convicted of bestial crimes, it sets a very dangerous precedent when the the state is licenced to take the life of the citizens of their choice. Better on balance to lock them up forever, imperfect though that alternative may be.
My sister-in-law Annette phoned from Toronto yesterday. Inter alia, she mentioned a case which is rocking Canada. Coloned Russell Williams, the commander of the biggest Canadian airforce base, CFB Trenton, has been found to have been pursuing a secret life as a prolific serial killer with a fetish for womens underwear. This is a man who was on a fast track to the very top and who has piloted the Queen and Prince Philip.
There are a myriad of references all over the web and a legion of YouTube videos.
http://www.mirror.co.uk/news/top-stories/2010/10/20/british-born-colonel-david-russell-williams-murdered-and-raped-to-satisfy-a-fetish-for-women-s-lingerie-115875-22645814/