How did the police know you were near a crime scene? Google told them

Tony Webster:

The suspects in an Eden Prairie home invasion last October wore gloves, dressed in black, and covered their faces with masks. But despite their efforts to remain unseen, a trail of evidence was left behind — not at the crime scene, but with Google.

Knowing the Silicon Valley giant held a trove of consumer mobile phone location data, investigators got a Hennepin County judge to sign a “reverse location” search warrant ordering Google to identify the locations of cellphones that had been near the crime scene in Eden Prairie, and near two food markets the victims owned in Minneapolis and St. Paul.

The scope of the warrant was so expansive in time and geography that it had the potential to gather data on tens of thousands of Minnesotans.

The technique has caught the attention of civil liberties lawyers who worry such warrants — deployed increasingly by police in the Twin Cities and around the country — are a digital dragnet ripe for abuse, and that judges may not realize the technical details or broad scope of the searches they’re authorizing.

“What is so problematic is that it can scoop up completely innocent people who are in an area for legitimate reasons, and who should not be treated as suspects,” said Teresa Nelson, legal director of the ACLU of Minnesota.

Many taxpayer supported K-12 school districts use Google services, including Madison.