MIRAMAR (CBSMiami) – The U.S. Postal Inspection Service offered a reward of up to $25,000 for information leading to the arrest of the criminals responsible for the robbery of a postal worker on the day after Christmas.

There have been more than a half dozen attacks on postal carriers in the North Miami area in the past two years. Most have been victimized for their master keys to mail boxes. That was the case with veteran carrier Bruce Parton, who was shot and killed on December 6th, 2010 while on his mail route.

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The latest robbery happened about 12:40 p.m. on Dec.26th of last year at an apartment building in North Miami at 14050 NE 6th Avenue.

Thieves targeted Concepcion Martinez, 66, in an area that has seen two postal workers attacked in two months. The thieves reportedly got away with Martinez’s key ring that included a master key to mail boxes. But the robbers were for the first time caught on surveillance video.

“Very fortunate in this most recent robbery to actually have surveillance footage,” said postal inspector Ivan Ramirez. “We have surveillance footage from the location of the apartment building where this letter carrier was robbed, but also some of the residents down the street.”

The suspects are believed to be between the ages of 18 and 20-years-old and they took off from the scene in a black compact car. Postal inspectors said there may have been a third person in the car as well.

“We implore anybody who may any information or have any knowledge or even maintain a surveillance system in their home for their own protection; folks, the letter carrier, mailman if you will, they’ve always been an institution and been part of our family and we have to look out for them,” Ramirez told CBS4’s Peter D’Oench.

Martinez has since returned to work and said she was not seriously hurt during the attack, but would like to see the criminals who targeted her caught. Postal Inspector Blanca Alvarez said the main concern of the staff was Martinez’s safety.

“Our main concern about these robberies is the safety of our employees,” said Alvarez. “Our number one concern of the U.S. Postal Inspection Service is the safety of employees and the security of our mail.

Alvarez told D’Oench, “We believe people are taking these keys to look for items of value in the mail, such as money orders and checks and gift cards.”

Thieves have also been looking for data in mail that they can use for identity theft. “Every day people come up with new ways to scam other people.”

“These keys are the keys to a financial future and stealing identity,” said Ramirez.

It’s not known if any of the cases in the past two years are connected.

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Postal carriers have told D’Oench that they are troubled by the attacks. They say they have been told by the postal inspection service not to speak to the media.

But on October 29th of last year, one carrier who asked that we not identify him said, “It could happen to me and I just pray to God that I can go home, go home to my wife. It’s a sign of these times.”

That carrier told D’Oench, “I feel disgusted. It’s juveniles. Mainly juveniles. And they’ve got impunity. And I feel there’s a lack of police around this area. There’s a lot of crime and you need protection.”

North Miami residents who we spoke with are concerned.

“It’s really irritating,” said Lesley Lee. “They are just doing their job. They are not hurting anybody.”

“It’s terrible,” Al Candelario. “I wouldn’t wish to see anyone get attacked.”

According to a police report obtained by CBS4, on October 26th of 2012, 61-year-old letter carrier Comilla Towns Jr. was putting mail in the mail boxes at an apartment building at 13280 N.W. 6th Ave. at 5:45 p.m. when he was approached by two juveniles who were between 14 and 16 years old.

The taller juvenile hit Towns on the right side of his head, causing a one-inch cut.

On Dec. 6, 2010, veteran carrier Bruce Parton was shot and killed while on his mail route at 486 N.W. 165th St. Road. His master keys for mail boxes were taken.

On Nov. 17, 2011, a carrier delivering mail to the people who live on NW 12th Street in Hialeah was attacked by a man who smashed her head with a pistol. Two men took a necklace and all of her keys.

On Feb. 21st of this year, U.S. postal Service inspectots said a postal worker who parked her vehicle near NW 158th Street and NW 2nd Avenue was attacked by two young men as she was leaving her vehicle. They also took a master key.

Following a series of robberies in October 2011, U.S. Postal Inspector in Charge Henry Gutierrez said, “We are changing our system. We are in the process of changing the system and the way we lock these boxes throughout the country and South Florida is in the process of doing that right now.”

Putting that in perspective, he told D’Oench that with more than a quarter million mail carriers on the road nationwide, the theft of master keys is extremely rare.

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If you can help with this latest case, you will be eligible for the reward of up to $25,000. Call the U.S. Postal Inspection Service at 1-877-876-2455 and select option #2.

Peter D'Oench