BY SUSIE CURRIE — Why did it take nearly seven weeks for Prince George’s County Police Department officers to identify a suspect in the October 29 armed-robbery and sexual-assault spree near Northwestern High School? Because eight hours after the attacks, he was in jail after attempting another armed robbery in Montgomery County. But it was DNA from a Montgomery County sex assault earlier in 2013 that led detectives to 33-year-old Emerito Chicas-Savala of Silver Spring. When it matched DNA from the local crime scene, county detectives obtained a warrant for him on December 13. He faces dozens of charges, including first- and second-degree rape as well as armed robbery.