The high-tech tools used to track down Nick Reiner after his parents' slayings

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It didn’t take long for police to focus on Nick Reiner after his parents were found fatally stabbed in the master bedroom of their Brentwood home Sunday afternoon.The challenge became finding him.Reiner lived in Rob Reiner and Michele Singer Reiner’s guesthouse but was not there when police arrived around 3:30 p.m.Prosecutors now allege he killed his parents sometime early Sunday.Detectives got a break in the case when they determined Reiner had checked into the Pierside Santa Monica hotel sometime after 4 a.m.
Sunday.But when they arrived in the afternoon, according to sources familiar with the investigation, he was gone.So authorities turned to digital geolocation to determine his whereabouts, said the sources, who spoke on condition of anonymity because they were not authorized to comment to the media.
Police began looking at Reiner’s movements across Los Angeles around 7 p.m.Sunday using location data from his cellphone, along with other electronic devices, app footprints and a network of cameras.The sources said Reiner moved quickly across the city during that period, eventually ending up in the Exposition Park area near USC, and was arrested around 9:15 p.m.
by L.A.police gang and narcotics detectives as part of a fugitive task force.
Officers filmed the arrest, which was also captured on gas station cameras.California Nick Reiner, 32, appeared in a Los Angeles courtroom on Wednesday morning, roughly 72 hours after allegedly killing his parents — beloved Hollywood figures Rob and Michele Reiner — inside their Brentwood home.It is unclear whether Reiner used public transportation that day or why he traveled to South Los Angeles.
But both the hotel and the area where he was arrested are easily accessible from the Metro Expo rail line.Law enforcement officials and prosecutors have offered scant information about the crime itself and how authorities came to focus...