jondrew lachaux , from las vegas , is assaulted the teenager and she had become pregnant , but she did not know , reports the review journal .
a 39-year-old man impregnated his 17-year-old stepdaughter who gave birth alone at home while looking after her three-year-old sister , who then died in her care .
jondrew lachaux -lrb- right -rrb- is married to the teenager 's mother 38-year-old kellie phillips , -lrb- left -rrb- and phillips decided to go on a road trip in california for over six months .
they rented a vehicle which did not have enough space for all the family , so they left the teen and her three-year-old sister behind .