A badly decomposed body was found in a vacant lot on Janesville’s south side Sunday.

Police said they don’t know if foul play was involved, but they didn’t think anyone in the neighborhood was in danger.

A resident called shortly before 2 p.m. to report what she thought was a dead body in the partially wooded lot at the corner of Burbank Avenue and Pierce Street, one block from Beloit Avenue, said Janesville police Sgt. Dean Sukus.

Sukus said police have an idea who it could be, based on missing-persons reports, but he would not say who that is.

A neighbor watching police from the sidewalk said he was sure he knew who it was, a man who had been despondent.

Police were on the scene for more than four hours, mostly hidden from news media and neighbors by trees and undergrowth.

Police and the Rock County Medical Examiner’s Department are working to identify the deceased and the cause of death, Sukus said.

The body likely had been there more than a week, and its condition hampered efforts to identify it, Sukus.

Sukus said the body was that of an adult, but he would not say if it was a man or woman. Sukus said investigators’ questions will include whether the person died there or the body was moved there.

An autopsy will be conducted sometime this week, Sukus said.