"The investigation will continue," the source said.
The tracker was found in Puigdemont's car during his trip to Europe in the spring. Representatives of the politician turned to Belgian law enforcement agencies to request an investigation.
While the probe was launched, it became stalled over lack of evidence.
The Efe news agency has reported, citing sources, that the tracker was planted by Spanish security services.
Puigdemont fled Spain shortly after the Catalan independence referendum, which was organized by his government in October 2017. Madrid called the referendum illegal and dissolved the Catalan parliament in response. A number of former Catalan officials were later put on trial, and a warrant for Puigdemont's arrest was issued. However, Spain's Supreme Court dropped the European arrest warrant against him and several of his aides in July of the following year.