MEXICO CITY -- Investigators in Mexico are expanding their search for three Italian men missing for nearly three weeks in Jalisco to the neighbouring states of Michoacan and Colima, authorities said Tuesday.

Officials say the probe is pursuing multiple avenues: the Italians' apparent commercial activities, a report that they were stopped by police before they went missing and the possibility of involvement by organized crime -- though none of these has been confirmed as related to the disappearances.

Search posters distributed online in Mexico have identified the men as Raffaele Russo, 60, son Antonio Russo, 25, and nephew Vincenzo Cimmino, 29, from the Naples area. They went missing in the town of Tecalitlan while travelling in two white SUVs, which have not been located.

Jalisco Attorney General Raul Sanchez said at a news conference that the investigation was initially slowed because a relative had reported the missing men as tourists, but investigators learned the men had apparently been selling knock-off appliances.

"Electric generators, welding equipment and different tools ... which were being sold as originals with prestigious brand names but were altered, apparently Chinese," Sanchez said. "The direction changed."

"Due to that we intensified the investigation more, without ceasing, without ceasing to investigate what has been said ... of the municipal police of Tecalitlan, where one of them, there is an apparent phone call saying a motorcycle and a patrol told them to follow or to make a stop," he added.

State authorities took over control of policing in Tecalitlan from the local force Tuesday.

Sanchez said officials have not ruled out that the men's commercial activities may be related to the disappearances.

The area is dominated by the Jalisco New Generation drug cartel.

Sanchez said the elder Russo was detained three years ago in the state of Campeche, on the Yucatan Peninsula, but did not give details.

Officials also met Tuesday with Italian diplomats to share information and update them on the progress of the investigation.

The previous day, Jalisco Interior Secretary Roberto Lopez Lara said federal organized crime prosecutors may take over the case.