A 34-year-old man and accused serial killer has been charged with the murders of four women in Detroit. Deangelo Martin is charged with four counts of first-degree murder and four counts of felony murder, NBC News reports. The women’s bodies were found in abandoned houses across the city—they were all discovered face down with used condoms beside them. The women have been identified as Annetta Nelson, 57, Nancy Harrison, 52, Trevesene Ellis, 55, and Tamara Jones, 55. Nelson and Harrison are believed to have died of blunt force trauma, but the cause of death for the other two is undetermined because their bodies were too badly decomposed. Police are investigating two additional possible homicide cases that could be connected. “I think it’s pretty clear that we believe he is a serial killer,” said Wayne County Prosecutor Kym Worthy. Police have said they believe all the women victims were sex workers.