Polish authorities have opened an investigation into the death of former deputy prime minister Andrzej Lepper, who was found hanged last week.

Police suspect his death was a suicide. A spokesman said Monday there is no evidence that anyone else was involved but that an investigation is necessary to confirm this.

Police officials say Lepper's body was found in his Warsaw office Friday and that everything indicates he killed himself. He was 57 years old.

A former pig farmer, Lepper was a member of the populist Self-Defense Party, which became a junior partner in a conservative nationalist government that held power from 2006 until 2007. He served as deputy prime minister and agriculture minister in that government, which was led for most of its short tenure by then-prime minister Jaroslaw Kaczynski.

Lepper was removed from his posts after he was linked to a corruption investigation.

Last year, Lepper was found guilty of demanding sexual favors from female members of his party and was handed a jail sentence against which he appealed.