Human Rights Watch says witness for its report on mass killings in Egypt last summer detained

Human Rights Watch says one of the witnesses for its investigation into mass killings in Egypt last summer has been detained.

The New York-based group said in a statement Monday that the witness, Mohammed Tareq, was detained during a protest in Egypt's second-largest city of Alexandria on Friday and ordered held pending an investigation. The group said Tareq's arrest appears unrelated to his testimony on last summer's violent security force breakup of sit-ins by supporters of ousted President Mohammed Morsi.

But the group said among four others detained with him, Tareq was the only one who was beaten and had his home raided, signaling that he may be targeted for his testimony.

The group called the 2013 security crackdown a likely crime against humanity.