Over the course of Brian Hickman's nearly 40 years of service with the Braintree Police Department, he performed many roles, from patrolman to detective.

But the police work that Hickman will miss most is being a juvenille officer.

"Helping teenagers who come from single parents... letting them know that police officers are human beings too – that’s really putting the frosting on the cake," Hickman said, reflecting on his retirement that took effect Sept. 12.

Hickman joined the department in 1973 and earned his first commendations soon thereafter, when in 1975 he was praised for arresting those involved in a break-in at the old Highland's Pharmacy. Over the years, Hickman served on a drug task force, as a detective and was appointed the department's juvenille officer in 2007.

"He served his community well for almosty thirty-nine years and I hope you will join me in wishing him a happy and healthy retirement," Lt. Michael Moschella, Interim Chief, wrote in a department letter.

Hickman, a West Roxbury native who moved to Braintree about 17 years ago, decided to retire this month following an accident in his cruiser earlier this year that left him with the lingering effects of a concussion and other head injuries. His father, also a police officer, once told Hickman that he'd know when it was right to move on.

"I knew it was my time," Hickman said.

He will spend more time with his family to make up for years of working 70- and 80-hour weeks, Hickman said, and might look for a job as a hotel greeter or something similar, a gig where he can continue to interact with and learn from people. Hickman and his wife Karen have two grandkids and four children: Stacey, Leigh, Matt and Brian Jr.

Aside from his work as a juvenille officer, two cases stood out for Hickman during his long career. Both happened while he was a detective and both involved murder, a rare crime in Braintree.

In 1987, Hickman was among those who arrested Matthew (Kyle) O'Connell for the murder of Julie Hamilton, a 22-year-old from Weymouth whose body was found stabbed and buried in Braintree. A year earlier, he also helped bring in William E. Buckley, who was charged with raping and killing a woman and leaving her body behind the Dairy Mart on Hayward Street.

Hickman was also commended in 1994 for disarming a youth with a knife while off-duty, in 2001 for arresting a man who had pointed his firearm at Hickman, and in 2005 for reviving a heart attack victim. In total, Hickman received 34 commendations and 42 letters of appreciation from individuals and organizations throughout his career.

"My whole career was a great ride," Hickman said.

During his recovery from the January accident, Hickman said he was supported by friends and family, and in particular by former Chief Paul Frazier, Mayor Joseph Sullivan, Deputy Chief Russell Jenkins, Interim Chief Michael Moschella and Lt. Karen MacAleese.

When Hickman joined the force, 39 years ago, there was no MBTA Station, no Shaw's Supermarket and less development in general. Then, all of a sudden, the town exploded with growth.

"It went from a small town to a small city," Hickman said. "I couldn’t get over how quickly the time went by."