mark howe , 21 , researched what weapons his tv icon used on victims .
sent text messages to friends saying how much he hated mum tina .
the 48-year-old tackled him over cannabis use at family home in leicester .
found lying dead inside flat by her father-in-law brian wardle .
kris wardle said he was devastated at death of his beloved wife .
kris wardle and his father brian appear on britain 's darkest taboos , sunday night at 9 pm on ci .