Black Hawk County Attorney Tom Ferguson issued the subpoena for the video of an interview KWWL-TV, Waterloo, conducted last week with Misty Cook-Morrissey and Wylma Cook, whose daughters disappeared earlier this month while riding their bikes in Evansdale.
The subpoena did not mention any specific information investigators were seeking other than to state the two women might know something about an unspecified criminal offense, KWWL said Thursday.
Lyric Cook-Morrissey, 10, and Elizabeth Collins, 8, were last seen July 13 riding bikes near the Collins home. The abandoned bikes turned up later near a lake.
The FBI Thursday issued a public appeal for a person witnesses said was on the lake July 13 to contact them, The Des Moines Register said.
"They [investigators] have had several people who think someone was [paddle-boating on the lake], but they're still looking for someone who was said to be out there," FBI spokeswoman Sandy Breault said.