To analyze attempted child abductions by strangers in Chicago and Cook County, the reporters linked computerized police records with court and U.S. Census data. Reporters also pored through thousands of pages of court and police files, and interviewed scores of victims, perpetrators and experts.
While the results offer new insights into this crime, all datasets have limits and potential weaknesses, and the Tribune believes it captured only a portion of the stranger child abduction attempts that actually occurred in Chicago and suburban Cook County.
The newspaper took these steps took to gather, verify and analyze the information:
By mining the Chicago Police Department's online CLEARMAP database of preliminary police incident reports, which is posted at http://gis.chicagopolice.org, reporters identified 407 reports from March 2008 through September 2010 that police initially coded as "CHILD ABDUCTION/STRANGER."
That dataset likely underreports the number of child abduction attempts by a stranger because Chicago police may initially classify some cases under different crime categories, such as sexual assault or battery.
In addition, police routinely re-code cases as investigations proceed and more facts emerge — a missing child report might become an abduction investigation, for example. And some cases could have been lost through "slippage" as the Tribune mined the CLEARMAP Web site.
The Chicago Police Department reported 366 stranger abduction attempts in the city's official crime statistics for the same time period. In response to Tribune queries, the department said it had investigated dozens more incidents each year than the Tribune found, but excluded cases where detectives determined a crime did not take place or did not precisely fit the child abduction statute. The Tribune could not determine from police files why authorities excluded some of these cases.
Child abduction attempts by strangers also can go unreported to police. Residents in low-income African-American neighborhoods and Hispanic immigrant communities sometimes lack confidence in authorities, according to political leaders and criminologists. And some youth don't tell their parents or other adults about abduction attempts because they fear reprisal from the predators, are ashamed they were targeted or don't want parents to restrict their freedoms, child safety experts say.
For each of the 407 reported incidents, the CLEARMAP data showed the date, time and location of the occurrence, the nature of the location — such as whether it occurred at a school or on the street — and other information, including the Chicago police report number.
Using the Freedom of Information Act, Tribune reporters obtained complete police files, including detective and supplementary reports, on the most recent 50 of the 407 cases, as well as two-page incident reports with narratives on another 100 incidents citywide. These underlying paper reports added information about the victims, perpetrators and incidents, and showed that the computerized CLEARMAP data were accurate in calling episodes stranger abduction attempts and not domestic conflicts or other crimes.
The Tribune filed FOIA requests with 80 Cook County suburbs that had a population over 10,000 and obtained 123 suburban police reports on stranger abduction attempts, as well as 47 additional reports in which the accounts did not appear credible or did not meet the requirements of the state's abduction statute. The newspaper did not request records from smaller suburbs or from sheriff's police patrolling unincorporated sections of Cook County, but the suburbs surveyed hold about 90 percent of suburban Cook County's population.
The Chicago CLEARMAP data and the suburban police reports enabled reporters to identify the Cook County criminal court files for the 30 cases in which an arrest was made following a police report of a stranger abduction attempt since 2008.
The newspaper also identified more than 70 other Cook County criminal prosecutions since 2000 in which charges were brought stemming from a stranger child abduction attempt. To find those cases, reporters compiled case lists and databases from the Illinois Department of Corrections and the state police sex offender registry for offenders who had convictions stemming from the abduction or kidnapping of a child. The Tribune also queried the Cook County State's Attorney's Office, which provided a list of prosecutions.
Finally, the Tribune linked the court and Chicago CLEARMAP case reports with U.S. Census datasets showing basic demographic characteristics of the census tracts where the incidents occurred. Reporters compared the tracts where no stranger child abduction attempts were reported with tracts that had reports but no arrests, and those where charges were brought.
Reporters analyzed census characteristics including race, median income, percent of the population that was age 14 or younger, percent of female-headed households and households on public assistance.
To get tract-level census data, reporters used 2000 census data, as more recent census information was not available at the tract level. The 2000 census data provides an imperfect match with crime reports from 2008-2010, since the characteristics of some Chicago census tracts shifted during those 8 to 10 years.
To compare the rate of arrests per reported incident for other crimes, the Tribune also linked census data with CLEARMAP reports on other crimes: homicide, aggravated sexual assault and attempted sexual assault. The newspaper did not find the same socio-economic disparities in the arrest rates for those crimes.
At Trib Nation, reporters Gary Marx and David Jackson discuss how they collected and analyzed information for this story. Read more >>