The son of a Boston police captain was sentenced Wednesday to 20 years in prison for an ISIS-inspired terrorist plot — three years after his father tipped off federal law enforcement.

Alexander Ciccolo, 26, went by the name Ali Al Amriki. His father, Robert Ciccolo, noted his son's admiration of the terrorist group and alerted the FBI.

The younger Ciccolo was arrested in July 2015 after a sting operation in which he accepted firearms that were illegal due to an earlier conviction. He was also recorded discussing plans that involved filling pressure cookers with black powder, nails and ball bearings, according to the federal prosecutors' statement. When law enforcement searched his apartment, they found partially made Molotov cocktails.

In May, Ciccolo pleaded guilty to providing material support to a foreign terrorist group, attempting to use weapons of mass destruction, possessing firearms and assaulting a nurse during a jail intake process.

"Alexander Ciccolo planned to kill innocent civilians in the United States on ISIS's behalf," prosecutor Andrew Lelling said in the statement. "Even though he was born and spent most of his life in Massachusetts, Ciccolo decided to turn against his country and plotted to attack his fellow Americans."

Robert Ciccolo has 35 years of experience in state and local law enforcement and private organizations, according to a LinkedIn profile. He oversaw more than two dozen officers during the Boston Marathon bombings, according to CBS.

His son was said to have been inspired by the marathon bombers.

Federal prosecutors acknowledged the captain's hardship in informing authorities about his son. "The government recognizes that Captain Ciccolo's decision to come forward was heartbreaking," they said in a sentencing memorandum filed Friday. But because of that "agonizing" decision, Ciccolo "likely saved the lives of numerous innocent people."

"Obviously, he struggled with [his son], and he couldn't set him straight," Boston Police Commissioner William Evans told WBUR in 2015. "Maybe now getting locked up was the best thing. Maybe he'll get the proper medical care he needs."

Ciccolo's mother, Shelley MacInnes, told New England Public Radio in 2017 that she did not agree with her husband's decision to go to the FBI. She said her son struggled with addiction and "has a deep respect for all living things. I'm sure some people are out there saying, 'Yeah, right.' But he literally would not hurt a fly."

Ciccolo's parents divorced when he was young and he moved from his mother's home in Cape Cod to his father's home in Boston when he was 14, according to NEPR.

A spokeswoman for the Boston Police Department's Office of the Police Commissioner told NPR, "It would be a personal family matter so Boston police wouldn't officially comment on it." A spokesman said the captain does not want to speak with the media.

In addition to prison time, Alexander Ciccolo was sentenced to a lifetime of supervised release.

"Make no mistake," FBI Special Agent in Charge Harold Shaw said in the statement, "Alexander Ciccolo was a committed soldier of ISIS who wanted to kill innocent people at a United States university with assault rifles and pressure cooker bombs, not an unwitting dupe who didn't understand the gravity of what he was doing."

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