It wasn’t supposed to take Sybrina Fulton and Tracy Martin five years to write a book about the death of their son, Trayvon Martin. But their grief has made finding the words unbearable until now.

Martin’s parents collaborated to write “Rest In Power: The Enduring Life of Trayvon Martin,” published Tuesday by Spiegel & Grau. The book recounts the journey of two grieving parents, thrust into the spotlight by tragedy and on some days, still as close to their loss as the day he died.

“The calendar says five years, but it seems like just a few months,” Sybrina Fulton said in an interview with The Associated Press. “I know that we’re still healing.”

Writing the book wasn’t a healing experience, but it was therapeutic to know that writing it might help others, Tracy Martin said.

“It was hard because we relived this every time we had to go back and write something about it. … It stayed fresh,” he said.

Trayvon Martin, shot to death by neighborhood watchman George Zimmerman in a gated community in the central Florida suburb of Sanford weeks after his 17th birthday on Feb. 26, 2012, became a rallying cry for millions of black Americans seeking justice for the fatal shooting of an unarmed black teen. Trayvon Martin would have been 22 on Sunday.

His case – propelled by national news reports and social media – was the predecessor to the Black Lives Matter movement that came in response to similar killings, mostly by white police officers in cities nationwide. Trayvon Martin’s killer, who was not initially arrested, was later acquitted of murder by a jury, further inflaming racial tensions.

Martin’s parents say the shooting deaths of Michael Brown in Ferguson, Tamir Rice in Cleveland, Walter Scott in North Charleston, South Carolina, and others, have added to their grief. But comforting other parents has helped them heal.