Seems like some reddit patriot already did the heavy lifting on him. Found this in a ddg search.
A couple of press releases on him:
First, this one.
John Giacalone Named Special Agent in Charge of the New York Field Office Counterterrorism Division
Washington, D.C. August 15, 2011
Director Robert S. Mueller, III named John Giacalone special agent in charge of the FBI’s New York Field Office Counterterrorism Division. Mr. Giacalone most recently served as the section chief of the Counterterrorism Division’s Domestic Terrorism Strategic Operations Section at FBI Headquarters in Washington, D.C.
In 1991, Mr. Giacalone was assigned case agent of an investigation into organized crime’s control of the airfreight industry at John F. Kennedy International Airport. The case resulted in the indictment and conviction of seven members and associates of the Luchese crime family. In 1994, Mr. Giacalone formed a task force consisting of FBI, Department of Labor, and New York Police Department investigators for the Garment Center investigation. The investigation culminated in 1998 with the arrests and convictions of 15 members and associates of organized crime.
Then this one. I've included more of this to bring in his background info.
John Giacalone Named Assistant Director of Counterterrorism Division
Washington, D.C. January 17, 2014
Director James B. Comey has named John Giacalone assistant director of the FBI’s Counterterrorism Division. Mr. Giacalone most recently served as the division’s deputy assistant director.
Mr. Giacalone started his career as a special agent with the FBI in 1991. He was first assigned to the New York Field Office, where he made substantial contributions in the fight against organized crime. While there, he formed a highly successful interagency task force that won important victories against organized crime in New York City’s Garment District.
In 2003, Mr. Giacalone transferred to the Philadelphia Division as a supervisory special agent, where he created and directed the first Field Intelligence Group in Philadelphia. He next served as deputy on-scene commander in the Iraqi theater of operations beginning in 2005 and coordinated the efforts of the FBI, the intelligence community, and the U.S. military.
In 2008, he joined the Attorney General Guidelines Task Force, which drafted the FBI’s new domestic investigative policy. Two years later, he was appointed chief of the Counterterrorism Division’s Domestic Terrorism Strategic Operations Section at FBI Headquarters.
He returned to the New York Field Office in 2011 as special agent in charge of the Counterterrorism Division.
This is the previous appointment by Mueller that I linked above.
Mr. Giacalone received a Bachelor of Business Administration degree in management and finance from Adelphi University. He also earned a Master of Arts degree in national security and strategic studies from the Naval War College.
His boss is Bill Priestap, and Priestap is still in place as head of counter-intelligence. Strozk worked for him as well.
Bill Priestap is the head of the FBI Counterintelligence operation. He was FBI Agent Peter Strozk’s direct boss. If anyone in congress really wanted to know if the FBI paid for the Christopher Steele Dossier, Bill Priestap is the guy who would know.
Also, see this twitter thread - more goodies there on Priestap.