On the Trail of Blood (1970)

Major Kalas (Rudolf Hrusínský) from the Prague criminal intelligence service has been sent to a small town of Dubá in North Bohemia to help with the investigation of the puzzling death of a child. A gypsy boy has been killed three weeks ago and his body found under a rock. As the investigation continues, another dead boy is found. The boy has bled to death after someone cut his artery with a handsaw. Both deaths are obviously the work of a murderer - a perverted pedophile, sadist who gets sexual satisfaction from the sight of a young boy's blood.