Corpse (girl) hidden behind the wall / horror, thriller movie from 80's or 90's

There are only pictures living in my mind of this oldish, low budget horror thriller movie, i try my best to share every details about it I remember.

  • There are 2 brothers living in a small town, one of them is a bit mentally retarded, who sells jams (it looks like that the jam would be human flesh) in the town (everyone, including the sheriff knows about him). His elder brother protects him from hooligens who are making fun of him (they are maybe simple tourists (teenager boys girls who are making party or so)).

  • One day the retarded boy accidentally kills (I don’t remember how) one tourist girl and his brother helps him to hide the corpse behind the wall of their house. The sheriff searches for the girl (and I think he found it after a while at the house, but it costs his life too)…

-The elder brother tries desperately to help his retarded brother and there is a scene, where he cries because of the accident.

Thank you very much for your kind help!