The man who installed an electric fence that left two picnickers dead Sunday had assembled the parts and erected it by himself, and the home-made device carried a constant charge rather than the brief pulses typical of livestock fences.

Officials from the Ministry of Economy, Trade and Industry dispatched to the site in Nishi-Izu, Shizuoka Prefecture, found that the fence had been plugged into a 100-volt mains socket. It was also connected to a 440-volt transformer, so investigators suspect the man had in fact been putting a higher voltage down the cable.

The police seized the fence and transformer Wednesday. They are investigating whether the man should be charged with aggravated negligence resulting in the death of two men and injury of several women and children.

Questioned by reporters, one of the man's relatives quoted him as admitting that he failed to install a circuit breaker. He said this was "a mistake."

On Sunday, Masatomo Ozaki, 42, and his son, Raiku, 8, and Raiku's friend, Kaio Iwamura, also 8, were playing in a river in the town of Nishi-Izu when they suddenly started screaming and fell down.

Four others who entered the river to help them were also electrocuted. Ozaki and Tomohiro Iwamura, 47, died, while the others sustained injuries.