NEW : Libyan authorities investigating lawyer Melinda Taylor over documents . She and three other International criminal Court staffers were detained . The court said it was concerned about the treatment of its staff, including Taylor's arrest in Tripoli last month. Saif al-Islam Gadhafi stands accused of involvement in the deaths of protesters .
NEW : Libyan authorities investigating lawyer Melinda Taylor over documents . She and three other International criminal Court staffers were detained . They had gone to Zintan , Libya , to meet with Moammar Gadhafi 's son . Saif al-Islam Gadhafi stands accused of involvement in the deaths of protesters .