This combo made from undated photos provided by the FBI shows cousins Lyric Cook, 10, right, and Elizabeth Collins, 8, who have been missing since Friday, July 13, 2012. (AP Photo/FBI)

Officers have been retracing their steps as they continue investigating the disappearance of two young cousins in east Iowa.

Black Hawk County Sheriff Tony Thompson says investigators are still searching for any details that might have been overlooked since Lyric Cook and Elizabeth Collins went missing three months ago in Evansdale.

Lyric has turned 11 and Elizabeth has turned 9 since they were reported missing on July 13. Their bikes were found near Meyers Lake in Evansdale.

FBI officials have said they believe the girls were abducted.