Christian Brückner, the 43-year-old German prisoner now under investigation in the disappearance of British toddler Madeleine McCann more than 13 years ago, may have been involved in at least two other missing children cases. Police say they are looking into the 2015 disappearance of a 5-year-old girl in Germany the same year McCann disappeared and the disappearance of a 6-year-old German boy from Portugal in 1996. None of the children have ever been found. Police say that a witness has come forward who had a conversation over Skype with Brückner in 2013 in which he allegedly fantasized about kidnapping and raping young kids. The witness told Der Spiegel magazine that he said he would like to “catch something small and use it for days.” Brückner is currently serving a prison term for a variety of offenses and was first convicted of sex crimes in 1994 when he was found guilty of sexual abuse of a child, attempted sexual abuse of a child, and carrying out sexual acts in front of a child.