bob moses. who had been invited to visit her english class. he was 19 years old. >> in real life, real friendly, had a great smile. so, i just said would you like to have lunch. >> the answer was yes. lunch turn to dinner. one thing led to another. >> after i left, we communicated. we emailed. but before you know i said hey, i would like you to come over. possibly we have a relationship. >> it was october, 1998. >> she came without her son. she told me she wanted to check things out before she brought her son over here. so, she was here and we got married in december of that year. >> two months later, igor came to the united states. suddenly, bob had a family. the one-time bachelor was smitten with his young wife. and his new four year old son. >> you know a little boy running around having fun. it was fantastic. >> bob formally adopted igor. >> he was my son. you know? i wouldn't consider him anything else. >> and he meant it. in 2002, fate dealt the family a sucker punch, when igor suffered wha

detectives talk with bob moses and leave with more questions than answers. >> did y'all ever fight when you all remarried? >> i mean we had disagreements. i mean that's kind of why we're divorced. >> i did not think that this was going to be an easy case to solve. when dateline continues.