The families of three Americans arrested in July after crossing into Iran from neighboring Iraq say they have hired a prominent lawyer in Iran to work for their release.

The families of University of California, Berkeley graduates Shane Bauer, Sarah Shourd and Josh Fattal said in statement Sunday that they have retained attorney Masoud Shafii.

The statement says the families hope Iran will release the three Americans on humanitarian grounds but feel the need to prepare for possible charges.

Iranian prosecutors said Tuesday that the three remain under investigation.

The families maintain that they are innocent hikers who went astray.

Shafii previously represented two internationally renowned Iranian AIDS physicians convicted in January of taking part in a U.S.-backed plot to overthrow Iran's Islamic regime.