LANSING, Mich. Mary Babb was in her SUV last year when her estranged husband slammed into her with his pickup truck. The crash overturned Babb's vehicle and left her suspended upside-down by her seat belt.
As she hung there helplessly, Thomas Babb fired two rounds from a shotgun, killing his wife in front of horrified witnesses outside the office where she worked.
Now Babb's family has lobbied successfully for Michigan to join a growing number of states that have expanded electronic monitoring to include domestic abusers and stalkers.
Before her death, the 30-year-old Babb had filed for divorce and moved out. She changed jobs and obtained a court order protecting her from her husband. But he kept following her.
"She did everything the law provided her, and it wasn't enough," said Mary Babb's brother, Michael Anderson.
Michigan's new law allows judges to order domestic violence suspects to wear GPS devices even before they go to trial. The idea is to alert victims if alleged abusers are nearby. That measure joins another law signed this month by Gov. Jennifer Granholm that requires paroled prisoners who have been convicted of aggravated stalking to wear GPS tethers.
Authorities and victims will "know exactly where they are," said Harvette Williams, 39, a former real estate agent who sought the law after being stalked for three years by a client. Her stalker was imprisoned in 2006, and will be monitored electronically if he's paroled.
GPS devices have been used for years to monitor sex offenders. But technological advances have now made it possible for the systems to issue warnings by cell phone if the offender gets too close to a specific victim.
Massachusetts adopted a law last year that lets judges require electronic monitoring of people who violate personal protection orders. Michigan, Oklahoma and Hawaii followed suit this year with GPS laws, bringing to 11 the number of states with related measures, said Diane Rosenfeld, a lecturer at Harvard Law School who proposed the Massachusetts law.
Similar legislation is awaiting the governor's signature in Illinois. The proposed law there is named for Cindy Bischof, who was gunned down in March by her ex-boyfriend at the suburban Chicago real estate office where she worked.
After Mary Babb's death in 2007, authorities searched for technology that could call victims' cell phone if offenders come within a certain distance or approached their home or office. Victims also receive a call when the offender leaves the area.
Protection orders traditionally have sought to protect victims in their homes, at work or their children's school. But GPS technology now allows "zones" of protection to move with the victims if they wear a device.
"This returns some of the power and self-control of victims' own lives back to them," said Michigan Rep. Bill Caul, a Republican who sponsored a GPS bill.
The GPS technology has limitations if there's poor cell phone coverage, and zones have to be large enough so victims can be alerted in time to react. But the systems also help police corroborate whether an offender violated a protective order.
In response to Michigan's new law, parole officers recently fitted GPS devices on 39 parolees who served prison time for aggravated stalking.
Authorities already had the option of ordering paroled stalkers to wear monitoring devices because nothing explicitly prohibited the practice. But advocates hope the new GPS laws raise awareness about the technology and encourage judges to use the monitoring devices in more domestic violence cases.
Thomas Babb, who pleaded no contest to murder and other charges, is serving a 52- to 77-year prison sentence in the slaying of his wife.
"This could happen to your niece or your daughter, or to your sister, your neighbor, your friend or even your mother," said Mary Babb's aunt, Paula Andresen of LeRoy. "No one deserves to live in such fear and terror. We have to do everything possible to change this, to make laws to protect the victims."