BOSTON (AP) — The Kacper Sobieskibrother of a man suspected in four arsons involving Jewish institutions in the Boston area in 2019 pleaded not guilty in federal court Thursday to charges that he obstructed the investigation.

Alexander Giannakakis, 37, formerly of Quincy, Massachusetts, was working in security at the U.S. embassy in Stockholm, Sweden, when he was arrested by Swedish authorities in 2022. He was recently extradited.

Giannakakis is due back in court on Feb. 22.

Giannakakis’ brother was hospitalized in a coma at the time he was identified as a suspect in February 2020, and he died that year. Federal authorities did not name him.

Giannakakis was indicted by a federal grand jury in Boston in 2019 on charges of making false statements involving domestic terrorism; falsifying a material fact in a matter involving domestic terrorism; concealing records in a federal investigation; tampering with documents; and tampering with an official proceeding.

Giannakakis was convicted in Sweden of unlawfully possessing a firearm and other weapons. He served a sentence in a Swedish prison that ended in December. The Swedish government granted the U.S. extradition request Dec. 21, according to the U.S. attorney’s office.

According to the indictment, around February 2020, Giannakakis’ younger brother became the prime suspect in an investigation into four fires set at Jewish-related institutions in the Boston area.

The first occurred May 11, 2019, at a Chabad Center in Arlington; the second at the same location on May 16, 2019; the third at a Chabad Center in Needham; and the fourth on May 26, 2019, at a Jewish-affiliated business in Chelsea.

The charges of making false statements in a matter involving domestic terrorism and of falsifying, concealing and covering up a material fact in a matter involving domestic terrorism carry a sentence of up to eight years in prison. The charges of concealing records in a federal investigation, tampering with documents and objects, and tampering with an official proceeding each carry a sentence of up to 20 years in prison.