The protest outside Police Headquarters had all but ended when the man in a Philadelphia Fire Department uniform appeared. He bent over a notepad perched on a concrete barrier and added his name to a list of people waiting for their loved ones’ murders to be solved.

John Gonzalez’s mother, Elena Irizarry, was killed in 1996, he told me, rising emotion blurring his words. His father owned a bar near Second and Girard. They were robbed.

“I gave up about maybe 10 years ago,” he said before being unable to say much more.

He walked off, head bowed and arms buried deep in his pockets, past the black plastic bags that organizers of the protest had fashioned into body bags and tagged “Unsolved.”

The gathering held three evenings in a row last week was organized by one grieving mother, Lisa Espinosa, as a silent protest against the city’s staggering number of unsolved murders, an opportunity for those who stood outside the Roundhouse to send a clear message to the men and women inside that they weren’t giving up and were counting on the officers to do the same.

They let their signs do the talking.

“Justin Reyes, unsolved 8 years.”

“Alexander Martinez, 7 years.”

“Kristian Hamilton-Arthur, 2 years.”

“Mario Pedro, 4 years.”

“Troy Smith, 5 years.”

“Michelle Gonzalez, 8 years.”

“Ryan Dillon, six months.”

“Remember me?” his mother had written underneath.

Turns out, even silence has a sound, and when an unexpected visitor showed up on the second day, it spilled out in frustration, anger, grief — and hope. Hope that the appearance of acting Police Commissioner Christine Coulter meant more than a convenient photo-op for the woman vying for the city’s top cop job.

They wanted answers:

Why do nearly half of the city’s homicides go unsolved?

Why is it sometimes nearly impossible to get in touch with detectives?

Why did it seem as though their loved one’s deaths were treated with less urgency than those with lighter skin or better neighborhoods or connections?

Why, asked Cheryl Pedro, had the detective on her son’s case told her during one of the department’s “next of kin” meetings that her son’s 2015 murder was now a cold case, his file buried somewhere in a basement?

Commissioner Coulter listened. She held some of the grieving mothers’ hands as they told her about the moment they learned their child had been killed, the pain of feeling as though their lives didn’t count.

“What I’m hearing is that we have to be way better,” Coulter told them.

She promised they would, but she also said it would take a community effort, and she’s right — to a point. Many of the people standing before her had long taken to the streets, to neighborhoods where victims and perpetrators sometimes lived right next door. They regularly implored their communities to help them put killers away. Grieving loved ones turned homicide detectives, by necessity.

The families had delivered their message loud and clear. And now I wanted to know what message Coulter planned to pass on to her detectives.

“First, I’m going to attempt to be clear to all of [the detectives] that these are real people and real families, and I know that they’re busy, but busy is not an excuse to not make sure that you’re reaching out to folks who are hurting, and they want those answers just like we would if it were our family,” Coulter said.

Assurances aren’t action, but several of the mothers there later received a call from the department, as promised. And the following day, Coulter was back, this time with the head of the homicide unit, Capt. Jason Smith, who invited mothers with unsolved cases inside to talk and get updates on their cases.

Sandy Ross was one of them. She came with a sign for her son Virgil, killed in May.

Her hands shook as she removed it from the plastic bag she used to protect it from the rain.

“I’m new to all of this,” she said, apologizing.

Overcome by emotion, she held the sign offering a reward for information about her son’s case in front of her face.

“I’m OK,” she insisted through tears. “I’m OK.”

But of course, she wasn’t OK. None of them are.