MIAMI (CBSMiami) – The investigation surrounding former U.S. Representative David Rivera’s alleged ties to an illegally funded congressional campaign continues to tighten up with additional witnesses now helping federal agents, according to CBS4 news partner the Miami Herald.

Former Rivera aide Ivette Pinto and Expert Printing & Graphics in Doral have both decided to cooperate with federal officials involved with the case, according to the Herald.

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The case centers on former Democratic congressional candidate Justin Lamar Sternad, who has pleaded guilty in the case. Sternad’s campaign was allegedly used “as a proxy to undermine a political rival of Rivera.” The rival is U.S. Representative Joe Garcia, a Democrat.

Sternad, according to the Herald, had been cooperating with federal officials even before he pled guilty last week to his role in the scheme. He said he was “used by others,” according to the Herald.

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Expert Printing produced Sternad’s mailers and now say they worked with Ana Alliegro, Sternad’s campaign manager and close friend of Rivera. Alliegro was to be questioned by the FBI before she left town last October.

According to the Herald, Expert Printing is a longtime vendor of Rivera’s and other Republicans and “likely knows who delivered $15,000 in unreported cash and when.”

Rivera has not been charged in any way related to the current case involving Sternad. However, investigators have not cleared the former representative either. There is no timeline from federal agents on when the case may wrap up.

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