The mayor of a small town in southern Italy that became a model for immigrant integration was placed under house arrest Tuesday for allegedly aiding illegal immigration, a move that brought a wellspring of support for the mayor.

Italian financial police arrested the mayor of Riace, Domenico Lucano, as part of an investigation into the allocation of a half-million euros in public funds to house refugees and asylum seekers.

Authorities said the investigation also is examining allegations that fraudulent associations were set up so immigrants could take over trash disposal contracts and the arranging of marriages of convenience to help female immigrants remain in Italy.

Lucano's companion, Tesfahun Lemlem, also was placed under investigation and risks losing her Italian residency.

Locri prosecutor Luigi D'Alessio told Sky 24 that the 18-month-old investigation is much broader than what was contained in the arrest warrant.

Italian Interior Minister Matteo Salvini, who has taken a hard line on immigration, hailed the mayor's arrest on Twitter.

Accidenti, chissà cosa diranno adesso Saviano e tutti i buonisti che vorrebbero riempire l’Italia di immigrati!<a href="https://twitter.com/hashtag/Riace?src=hash&ref_src=twsrc%5Etfw">#Riace</a><a href="https://t.co/Ae1ROuMwA8">https://t.co/Ae1ROuMwA8</a> —@matteosalvinimi

But a hashtag that in English translates to "Riace won't give up" —​ #Riacenonsiarresta — was trending on the same platform with support for the mayor and his hospitable policy.

Hundreds of people gathered in Rome to support Lucano under banners reading "Solidarity is not a crime." Italian journalist and news show host Gad Lerner called the mayor's arrest "a slap in the face to those who practise the duty of welcoming."

The Calabrian town of Riace gained recognition for integrating hundreds of migrants into the town of fewer than 2,000 residents, starting with the arrival of a boat carrying more than 200 Kurdish refugees in 1998.

Listen to The Current's documentary about how an influx of refugees helped revive Riace:

After so many people emigrated from the small town of Riace Italy, mayor Domenico Lucano saw an opportunity for the near ghost town and decided to welcome migrants in search of a better life. Join us as we travel to Italy and meet the residents of Riace. 18:58

The town offered the newcomers housing in vacant properties that once housed Italians who had moved north long before.

As mayor, Lucano made accommodating immigrants and refugees central to his administration. His government opened schools to help them and offered micro-credit to start small businesses, including a recycling project run by two immigrants who used donkeys to go door-to-door to collect refuse.