MITSERO, Cyprus (AP) — Cypriot authorities say poor visibility in a man-made lake's toxic waters is hampering the search for a victim of a suspected serial killer.

Investigators believe a suitcase at the bottom of the lake contains the remains of one of seven foreign women and girls that a Cypriot army captain has confessed to killing.

Fire chief Marcos Trangolas told The Associated Press on Monday that it's slow going for a robotic camera being used in the search. He said a sonar device will also be deployed.

The 35-year-old suspect said he put the bodies of three of his victims — a mother and daughter, and another woman — in suitcases and dumped them in the lake.

A suitcase containing the remains of an adult woman was retrieved from the lake Sunday.