CHICAGO – Authorities are trying to determine how a Chicago college student died, after her decomposing body was found inside a mattress in an apartment in the Pilsen neighborhood.

Michelle Manalansan was a 29-year-old student at Harold Washington College. She was last seen Feb. 9 leaving her home in the city’s North Loop area wearing a jogging suit and gym shoes.

Police found her body about a week ago inside a Pilsen apartment. According to a police report, her body was found inside an air mattress that had been cut open and stuffed with garbage.