Detective Conan S01 E517 Fūrinkazan - Shadow and Lightning's Conclusion

"One truth prevails."

Kansuke Yamato reveals that Shigetsugu hooked his fishing rod onto the railroads power lines resulting in his death. He shows them Shigetsugu's diary which explains that the four victims were the cause of Kuroto Kai's death and deduces the culprit who murdered the three victims.