were first neighbors. this woe grow up to become friends, then relatives by marriage. did he seem like a relative? yeah, i could sense that. he was really close with them. it wasn t just, like, a friend that you would see over. reporter: brittany dane lives two doors down from the home where farouk s father, brother and sister-in-law live. dane saw marquez frequently here. the home not far from this mosque, the islamic society of corona nor co-. members of the mosque tell cnn several years ago, marquez came here alone, saying he had cop verted to islam, but he only attended a handful of times. this is a mosque marquez listed on his december 2014 marriage certificate as his religious institution. his wife is the sister of the woman married to syed rizwan farook s brother. but to outsider, the marquez s marriage seemed unusual. it wasn t like they were married or anything, like he helped them, but it wasn t like