Within a month, law enforcement officials announced two major busts of robbery gangs suspected of targeting jewelry stores.

In May, 19 Michigan residents suspected of operating a nationwide grab-and-run ring that stole $1.2 million in jewelry were arrested and charged with conspiracy and interstate transportation of stolen property. An FBI complaint says the metro Detroit–based operation hit more than 45 stores in 22 states between May 2006 and April 2011 and routed the stolen items back to Michigan. (On June 9, a federal judge dismissed charges against four of the Michigan suspects, citing the government’s need to obtain further evidence.)

Also in June, a group of south Floridians was taken in for allegedly operating a ring of roof-top burglars who stole an estimated $6 million-plus of ­jewelry. Eight suspects were charged with racketeering and conspiracy to commit racketeering. A ninth suspect has not been apprehended, but authorities have active warrants for his arrest.

The gang is suspected of operating a ring with multiple crews that would cut holes in the roofs of ­jewelry stores and pawn shops, ­disable alarms, and then use torches to access the safe. Based in Miami-Dade County, Fla., the theft ring targeted stores in Florida, North Carolina, Tennessee, ­Virginia, West ­Virginia, and Connecticut.