U.S. News - Search for missing Arizona 6-year-old crosses into Mexico Tuscson, Ariz. police continue to search for a missing 6-year-old girl. NBC's Miguel Almaguer reports and NBC's Ann Curry talks with criminologist Dr. Casey Jordan about the case. By Becky Bratu, msnbc.com As the search for a missing Arizona 6-year-old spills into Mexico, police say one of the men captured on surveillance video leaving a club near Isabel Celis' home could be a key witness in the investigation. According to ABC News, police already have spoken with a few of the five people seen leaving the club around 1:30 a.m. on the night Isabel went missing. The club is just a block from Isabel's house in Tucson, and police want to know whether the group noticed anything unusual. The girl was last seen around 11 p.m. on April 20 as she was getting ready for bed. Her father reported her missing the next morning, when he noticed Isabel was not in her bedroom at 8 a.m. and saw the window was open and the screen had been removed. ABC reports that the search has crossed into Mexico, where U.S. marshals asked local authorities for assistance in the search for Isabel in the town of Sonora. "The idea that somebody crossed and picked up Isabel and then went back into Mexico is actually realistic," former FBI agent Brad Garrett told ABC. KVOA-TV reported that local artists recorded a song to raise awareness about Isabel's disappearance. "If anything ever happened to my little girl I would want the community to go out and basically do what ever they can to bring her home," artist Yung Joe told KVOA.