A Florida man who investigators say posted anti-Islamic material on social media has been arrested on charges of setting fire to a mosque attended by the gunman who committed the deadliest mass shooting in modern US history.
The case is being prosecuted as a hate crime under Florida law, and the suspect, Joseph Michael Schreiber, 32, faces at least 30 years in prison if convicted of committing Monday's arson attack, according to the St. Lucie County Sheriff's Office.
The case stems from the fire that heavily damaged the Islamic Centre of Fort Pierce, a place of worship for gunman Omar Mateen before he shot 49 people to death and wounded 53 others at a gay nightclub in June.
Mateen himself was killed by law enforcement officers at the end of the shooting in Orlando, about 100 miles (160 km) northwest of the Atlantic coast town of Fort Pierce.
Fire erupted at the mosque at about 12:30 am EDT on Monday, coinciding with one of the holiest of Muslim holidays, Eid al-Adha, or the Feast of Sacrifice, and authorities immediately branded the blaze an arson attack.
No one was inside the building at the time, but the blaze forced the congregation to move its prayer services.
The St. Lucie County Sheriff's Office told reporters afterward that surveillance video footage showed a man riding up to the building on a motorcycle, getting off the bike and approaching the mosque carrying a bottle of liquid and papers moments before flames erupted.
At a news conference announcing an arrest on Wednesday, Sheriff's Major David Thompson said Schreiber owns a motorcycle like the one seen in the video.
Mr Thompson said tips from the public led investigators to the suspect and his home in nearby Port St. Lucie, where a search turned up additional evidence tying him to the crime.
An examination of Schreiber's social media account also uncovered "multiple anti-Islamic posts and comments," Mr Thompson said.
He was arrested without incident on Wednesday while walking along a footpath in Fort Pierce, Mr Thompson said.
Schreiber, who was being held without bond, was still being questioned by police following his arrest. He was expected to make his first court appearance on Thursday. It was not clear if he had obtained legal representation.
He has been charged with arson, and his status as a "prison release re-offender" qualifies him for a mandatory minimum prison sentence of 30 years if convicted, authorities said. And as a "habitual felony offender" whose criminal record includes armed robbery, Schreiber also would be eligible for a possible life term in prison, according to authorities.
Federal authorities are also investigating the fire for any potential violations of federal law, US officials said.
The Fort Pierce Islamic Centre has reported numerous threats of violence and intimidation since it was identified publicly as Mateen's place of worship. In June a motorcycle gang circled the property and shouted at its members, and in July a Muslim man was beaten outside the mosque.