LUCKNOW, India (AP) — Federal investigators say they plan to exhume the bodies of two teenage girls raped and killed by attackers who hanged their bodies from a tree in northern India six weeks ago.

A top police official said Tuesday that the Central Bureau of Investigation plans to conduct a second autopsy after the cousins were found killed in Uttar Pradesh state on May 28.

The families of the girls demanded the killings be investigated by the federal agency to ensure impartiality.

Five men arrested in connection with the deaths and the girls’ family members have undergone lie-detector tests in the past week.

India has a long history of tolerance of sexual violence, but the attack on the girls has caused outrage across the nation.