L'AQUILA, Italy (CNN) -- A researcher says he predicted Monday's devastating earthquake that killed dozens of people and left tens of thousands homeless in central Italy, but authorities dismissed him as a scaremonger.

Rescue workers search for survivors in the ruins of a collapsed house in L'Aquila, Italy. more photos »

Gioacchino Giuliani, an employee at a physics institute at Gran Sasso, near the badly-hit city of L'Aquila, has demanded an official apology for what he says was an unforgivable failure to act on his predictions.

"There are people who must apologize to me, and they must have the weight of what occurred on their conscience," Giuliani said after the quake hit, according to local news site Ilcapoluogo.com.

Last month, vans with loudspeakers drove around the area broadcasting Giuliani's warning after he claimed his method of predicting seismic events by radon gas emissions had forecast an imminent quake.

The scientist was reported to police for spreading false alarms and was made to remove his findings from the Internet. "They called me an imbecile," he said.

According IlCapoluogo, Giuliani gave an interview as recently as March 24 in which he repeated his claims.

Local authorities have insisted Monday's 6.3-magnitude event was part of a sequence of tremors in a quake-prone area and neither the size nor the timing was possible to predict.

Giuliani said he was monitoring radon concentrations ahead of Monday's quake, but knew the authorities would press charges against him if he repeated his warning.

"last night I did not know who to talk to. I could see the situation was deteriorating and there was nothing I could do," he said, according to IlCapoluogo.

-- CNN's Barry Neild and Gisella Deputato contributed to this report

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