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Detectives of the Criminal Investigation Section are on call 24 hours a day, 7 days a week, 365 days a year working cases across St. Mary Parish.   

Detectives assist patrol deputies in investigations. Once a uniformed deputy takes a report, detectives may begin a follow-up investigation. The Criminal Investigation Section is responsible for processing and cataloging evidence at crime scenes. They interview victims, witnesses, and suspects as well as prepare affidavits for arrest warrants and search warrants along with other various investigation related duties.

In 2013, detectives investigated four homicides making an arrest or arrests in each case. The solved murder cases are a direct result of the efforts of detectives in collecting and corroborating evidence and submitting DNA evidence from the crime scenes to the Acadiana Crime Laboratory for analysis.

Information on suspected criminal activities or current investigations may be sent to detectives at or by contacting the Criminal Investigation Section at 337-828-1960 or 985-384-1622.


Gil Blanchard

Captain Duval Arthur III

Investigations & Narcotics





Captain Duval Arthur, III joined law enforcement in 2003 for the Berwick Police Department while also attending LSU. After graduating with a degree in Sociology with a concentration in Criminology, he accepted a position as a full-time law enforcement officer with the Berwick Police Department. In 2008, he accepted a position on the Narcotics Task Force at the St. Mary Parish Sheriff's Office. In 2016, Duval was promoted to the Rank of Captain supervising the operations of the St. Mary Parish Sheriff’s Office Narcotics Division. As a supervisor, he challenged the members of his division to continually strive to better themselves and the work they do in pursuing local drug dealers. In 2021, Investigations was added under his command.

Captain Duval also serves as a team leader and sniper for the Sheriff's Office Special Response Team.








Gil Blanchard

Captain Gil Blanchard



After graduating from Temple High School in New Iberia, LA Captain Gilbert Blanchard entered into the profession of law enforcement in 1993 with the Morgan City Police Department. He completed his basic law enforcement training at Louisiana State University in Baton Rouge. From 1993-1999, Blanchard worked as a police officer in the patrol division. In 2000 he was promoted to the Morgan City Police Department Detectives Division where he served for the decade. In 2011, Blanchard transferred to the narcotics division until his reassignment to patrol in 2012. During his employment with the Morgan City Police Department, Blanchard served on the Special Response Team and completed training in undercover investigations, instructor certification, kinesic interview, rape and sex crime investigation, raid planning, homicide investigation, video techniques, informant management, Asian organized crime, video surveillance, employment law, business writing, and human resource courses. In 2012 Blanchard accepted a position in the Uniformed Patrol Division of the St. Mary Parish Sheriff's Office, where he worked as a shift supervisor until he was promoted to Detective in the Criminal Investigation Section.

In 2016, Blanchard was promoted to Captain and placed in command of the Investigations Section. Blanchard was able to call upon his wealth of experience in criminal investigation techniques and procedures as he supervised the work of detectives, juvenile detectives, school resource officers (including DARE), and evidence custodians.