The Terror of Ivan Malat

Deborah and James Malat were last seen on December 30th, 1990. It's assumed that Ivan picked the friends up somewhere near Liverpool. Given what we know from hitchhikers who got away from Ivan, it seems plausible that he threatened the two unless Deborah agreed to have sex with him. With the threat of violence, it might have been easy for Ivan to convince the teenagers that he would let them go if they cooperated. Then by the time he had them tied up, it was too late.