This is one of our editors' picks from our ongoing roundup of Investigations Elsewhere.

The Chicago Tribune published its latest installment today in a series on the consequences of housing mentally ill convicted felons with the elderly in Illinois nursing homes. Today, the Tribune reports that there have been at least 86 investigations into allegations of sexual violence against nursing home residents in Chicago since July 2007 -- and just one arrest. Almost all of the allegations fingered fellow residents as the assailants.

The 48 most serious allegations, those involving rape, came from 30 nursing homes across the city. Those facilities “were roughly twice as likely to house convicted felons and mentally ill patients as the 89 city nursing homes without a sexual assault allegation,” reports the Tribune. In addition, most of those 30 homes were understaffed.

What’s more, those allegations of rape resulted in just one arrest; citywide, police made roughly one arrest for every three reports of rape in 2009. But the Tribune notes that “a variety of factors can interfere with investigating or prosecuting sexual assault reports in nursing homes. Often the victims suffer from dementia or appear delusional and can't describe the attacks in enough detail to assist investigators.”

Sometimes, faced with such obstacles, police drop investigations too early or “decide that mentally ill perpetrators lack the intent needed for successful prosecution,” according to experts interviewed by the Tribune. But the chief of detectives for the Chicago Police Department rebuffed those claims: "We're not real quick to drop investigations ... that's not the case. Sexual assaults are something we take very seriously."