Cover Story Can math stop murder? (+video)

In besieged Chicago, how police are tapping Big Data to try to curb gang violence.

By , Staff writer

/M. Spencer Green/AP/File

It was an unusual encounter from the start. On a cold evening in February, Chicago police officer Maria Peña knocked on the door of a house in one of the city’s most crime-ridden neighborhoods. She wanted to talk to a leader of the Latin Kings, a gang on the city’s South Side, as well as his mother. Ms. Peña was not there to question or arrest the man. She wanted to save his life.