Melissa Mason & Nicole Glass (6 of Hearts, Arizona)

On the afternoon of December 3rd, 2010, police in Phoenix, Arizona found the bodies of friends Melissa Mason and Nicole Glass, both 27, in the home they shared. Both women, who were killed in different parts of the house, had been strangled. What’s more, Melissa was eight weeks pregnant. Investigators quickly exhausted forensic leads and have yet to arrive at a motive for the triple homicide more than a decade later.