The case is being treated as a homicide.
About $4,000 in jewelry was reported stolen.
The thefts took place in Florida and Virginia.
The region has experienced an increase in robberies, many of them armed.
$1.5M in merchandise was stolen.
He also admitted to failure to file a record of financial transaction.
Among the items stolen were watches by Frederique Constant, Patek Phillipe and Tudor.
About 500 items were taken.
Police believe the crimes were all connected.
Armed robbers forced entry to the store on Tuesday and Thursday mornings.
The thieves have come to be known as the "Rolex Rippers."
The suspect discarded a bag containing additional devices and powder.
They used hammers to smash the display cases.
Authorities say the case involved "exorbitant amounts of pawn transaction."
The Jewelers' Security Alliance has released its annual report for 2020.
Thieves struck in Burlington, Everett and Medford.
Among the items taken were four custom chains worth $6,000 each, along with $10,000 in costume jewelry.
A group of nine suspects took over a jewelry store in a Hayward, CA, mall.
The burglary 'dealt a big blow to the establishment,' which has been in business for 38 years.
Police believe he stole from Kohl's and other stores in Kentucky.
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