cindy karlsen believed her husband, karl, killed their son, levi. ed from dateline cindy would soon take on a dangerous mission. confronting the situation. here is andrea canning with deadly deceit. >> in november 2011, private investigator, steve brown, decided it was time to meet karl karlsen. he and cindy came up with an audacious plan. >> i said what if i go undercover and befriend karl if you will as a marketer or promoter for your duck business. >> it was a giant step for cindy and risky. if karl found out who steve really was? >> no clue this was a private investigator? >> correct. >> when he came to the house, i had to pretend. >> where are you now? and karl started telling his vision, his dream for the duck business if you will. >> after that steve said he and karl would drive around the area talking business mostly. the one moment stood out when he was talking about farm animals. >> and he came up behind me and went like this with his hand and he said messy, very physical. i said karl, we are talking about ducks and chicken, aren't we? >> s