Tamer­lan Tsar­naev var gift med 23 år gamle Katherine Russell, som han traff mens hun studerte i Boston, og de to hadde en liten datter. En nabo forteller til Washington Post at Katherine begynte å kle seg på muslimsk vis:

One next-door neighbor, Paula Gillettte, said Katherine had gone through a dramatic transition in her dress since going to college in Boston. When she returned for visits, she was wearing a head covering and the long-flowing gowns of traditional Muslim women; she also stayed inside more.

Ruslan Tsarni, onkelen til de to terroristene, har følgende forklaring på det som skjedde:

Being losers — hatred to those who were able to settle themselves.