Story highlights Alexander Ciccolo was charged in a plot to engage in terrorism on behalf of ISIS

Investigators allegedly found several partially constructed Molotov cocktails in his apartment

Source: Ciccolo's father, a police captain, alerted authorities after his son allegedly made alarming comments

(CNN) A Massachusetts man was arrested and charged in a plot to engage in terrorism on behalf of ISIS, according to a criminal complaint unsealed Monday in federal court.

Alexander Ciccolo, who also goes by Ali Al Amriki, was charged with felony possession of firearms, the U.S. attorney's office in Massachusetts said.

His father, a Boston police captain, alerted authorities after Ciccolo made alarming comments, according to a law enforcement source. Robert Ciccolo has had minimal contact with his son since the younger Ciccolo turned 7, the source said.

"While we were saddened and disappointed to learn of our son's intentions, we are grateful that authorities were able to prevent any loss of life or harm to others," the family said in a statement, asking for privacy.

According to court documents, Alexander Ciccolo has a long history of mental illness and had become obsessed with Islam in the past 18 months.