Police revived a 1973 murder case by live-tweeting a girl’s last day. Now, a DNA match has led to an arrest.

On the day Linda Ann O’Keefe died, it was a cooler-than-normal July morning in Newport Beach, Calif. The brown-haired, blue-eyed 11-year-old got a ride to summer school — about half a mile away — but had to walk home in the afternoon.
It was July 6, 1973, a Friday. When O’Keefe didn’t return home right away, there was little concern at first. But when night fell and her whereabouts were still unknown, her parents called police and desperately combed the neighborhood, to no avail.