MANKATO-October 2, 2012-(KMKO)- A Mankato man, who witnesses said was having sex with his passenger as he was driving, pleaded guilty yesterday. 24-year-old Mark Anders Chalin, said he didn't remember anything about what led to the crash that killed 23-year-old Amber Menezes of Mankato and 35-year-old Jonna Martin of Lakeville in August 2011. Witnesses who had passed Chalin's car reported his view of the road was blocked when he slammed into another car driven by Martin.  Prosecutors will recommend a 48-month prison sentence.