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MIAMI (CBSMiami) – It's been a tough few months for the family of Jaime Humet.

The Miami-Dade librarian was murdered in December after going to an ATM at the Dade County Federal Credit Union on NW 2nd Ave and 207th street.  His killer is still on the loose.

"If we don't catch him, he's going to feel like he's bulletproof," his brother Nick Humet said. "He's just going to keep doing it and other people are going to get inspired by this kind of atrocity."

The family is suing the credit union, saying they should have had more security.

"Had the Dade County Federal Credit Union had the proper security on that night, in light of the prior history of crime in both the branch and the surrounding area, this incident would have never happened," said family attorney Pedro Echarte.

The murder happened December 10th of last year.

Investigators say Humet used the ATM and when he was leaving in his car, it was shot through the back window.

"Jimmy tried to flee the scene," Echarte said. "He accelerate on the gas pedal in his car, he tried to take off and this individual shot him, killing him on the spot. He died not a few feet away from where we're standing today."

Surveillance video captured a man running away in a black hoodie to a getaway car, a white Kia Optima.

The Humet family is pleading for information, hoping an increased reward will help.

"We need somebody to talk to us, to give the police a tip," said Nick Humet. "It can't be about, 'Oh I'm not going to snitch.' This is not snitching, this is survival. We gotta make our city safe for our family, for our friends."

The Dade County Federal Credit Union has issued the following statement:

At Dade County Federal Credit Union, we remain deeply saddened about the death of Jaime Humet, and we have fully cooperated with the law enforcement investigation. It is a longstanding policy of the credit union not to comment on pending litigation.

The reward is now up to $23,000.  Anyone with information is asked to call Miami-Dade Crime Stoppers at 305-471-TIPS.