The former owner of the iconic "Home Alone" house has died by suicide ... just days after he was busted on child pornography charges.

Authorities in Lake County, Illinois say 79-year-old John Abendshien was found dead Wednesday evening at a nature preserve ... and a preliminary autopsy determined he died from "asphyxia in a manner consistent with being self-inflicted."

The shocking twist comes less than two weeks after he was arrested and slapped with multiple felony charges tied to alleged child pornography possession. He had been released from custody with conditions after a detention hearing earlier this month.

Abendshien has ties to one of the most famous homes in movie history -- he previously owned the massive 671 Lincoln Avenue mansion featured in "Home Alone" for decades.

He previously told NBC Chicago he was actually living in the house when Macaulay Culkin and the cast rolled in to film the beloved 1990 Christmas classic ... before he eventually sold the property in 2012.

Now, the man linked to a holiday movie staple is at the center of a deeply disturbing final chapter.

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