Two teams from the Organization For Security and Cooperation in Europe (OSCE) remain missing after being detained in troubled eastern Ukraine.

Eight OSCE monitors and one translator were supposedly released by their captors, but none has been in contact with the OSCE. A four-person team was detained in Donetsk last Monday and a four-person team plus interpreter were detained in Luhansk Thursday. Despite the lack of contact, the OSCE is optimistic  the teams are not harmed and will return soon.

“We are quite confident they are in good shape, they haven’t been harmed,” OSCE special monitoring mission to Ukraine spokesman Michael Bociurkiw said Sunday. “We’re working through a number of channels and there’s positive signals from those that they’re OK.”

He went on to say the OSCE is in contact with various groups in the region to verify the location of its teams.

A major issue in securing their release has been the lack of central authority in eastern Ukraine. The separatist groups are not homogeneous. Their missions differ and some even criticize other groups as “looters” and illegitimate. Two of the major separatist groups, those under the self-proclaimed mayor of Slovyansk and prime minister of the Donetsk People’s Republic say they do not know where the teams are being held, nor do they have influence over their captors.

There have been conflicting reports as well. Before saying he could not influence the teams’ captors, the Slovyansk Mayor Vyacheslav Ponomarev said Thursday his people had custody of the observers and they would be freed shortly.

“They were the four most-zealous ones,” Ponomarev said of the monitors, “and they were detained.”

Violence in the region has further complicated efforts to find the monitors. Some 30 to 100 separatists were killed trying to take back the airport in Donetsk from the Ukrainian army, which wrested control from separatists on Tuesday. Six others were killed trying to retrieve the bodies of separatists from around the airport on Sunday.