When prosecutors dropped all charges against the men suspected of killing her son last year, Candice Lynch thought back to the day the other half of her heart was torn out.

Twice now she has had to do what no parent should: bury a child. In 2016, her son Derrick Mack, 18, was gunned down during an apparent robbery in north Minneapolis. Then last year another son, 26-year-old Daniel Mack, was slain on the North Side after several gunmen opened fire on the SUV he was in, police said.

In both cases, police made arrests. And each time, prosecutors chose not to pursue the case because of doubts about the evidence.

As if the pain of losing a second son wasn't unbearable enough, Lynch is tormented by the idea that Daniel's alleged killers are carrying on with their lives as if nothing happened.

"I was pissed, I was angry. I was very upset with the system," she said.

Police said that Daniel was shot on June 4, 2020, while riding around north Minneapolis with another man. The two friends, both of whom police say were Low End gang members, got into an argument with a group of men standing at the intersection of N. 34th and Dupont avenues, the territory of the rival Tre Tre Crips. Words were exchanged, and then gunfire.

A short time later, a nurse leaving North Memorial Health Hospital found Daniel dead inside a vehicle, which had been abandoned outside. Within weeks, authorities arrested and charged three of the four suspected shooters with second-degree murder.

At first, Lynch said, the victim's advocate assured her that the state's case against the men "looked good," and prosecutors were able to persuade a grand jury to upgrade the charges to first-degree premeditated murder.

But then in June, prosecutors abruptly announced they were dropping the case.

Lacey Severins, a spokesperson for the Hennepin County Attorney's Office, said that while she couldn't discuss certain elements of the case, she said prosecutors dismissed the charges "because the evidence changed profoundly from what was initially presented to us, what we based the complaint on and who we had witnesses for at the time of trial."

Prosecutors intended to call two witnesses, who previously had identified the alleged shooters, she said. But just before trial, one witness recanted his earlier testimony in an interview with a defense investigator.

"The witness was uncooperative with subpoena service and had to be arrested pursuant to a warrant to procure his presence for court," she said. "He vehemently claimed he would never testify. This happens in gang-related murders because witnesses fear retaliation."

A second witness vanished just before trial, she said.

Lynch's sister, Catrice Lynch, found it all hard to believe, given the evidence.

"If somebody gets up there and lies, somebody's going to be prosecuted," she said. "I've never heard of someone dropping a first-degree murder charge."

The lack of charges has frustrated Candice Lynch, who said she didn't think that authorities took either one of her sons' cases seriously.

Authorities say that on March 26, 2016, Derrick met with a man to buy a stereo near the corner of N. 39th and Colfax avenues — not far from where his brother was gunned down four years later. After a brief struggle inside the other man's car, Derrick was shot dead.

Police later arrested two suspects, ages 18 and 23, one of whom would later confess to firing the fatal shots, according to police reports. But prosecutors seemed convinced that the meeting was a robbery setup and said they believed the other man shot in self-defense — even after a private investigator hired by Lynch raised some questions about the case.

Daniel was crushed after his brother's death, Lynch says, and the two of them leaned on one another for support in the years that followed. Now, he, too, was gone.

Court records provide glimpses into the monthslong police investigation of Daniel's killing. With the assistance of the FBI, detectives obtained cellphone records for at least two of the suspects showing that they had been in the vicinity at the time of the shooting.

A witness told police that a group of Tre Tres had been on the lookout for "ops" or rival gang members when they spotted the vehicle Mack was riding in circling the block, the records show. The witness, who didn't see the actual shootout, said the men were armed and appeared to be waiting for the SUV to return. An informant also told police that one suspected gunman was at a house party holding a handgun with an extended magazine, a fact investigators later confirmed by watching the suspect's Facebook Live video, court records show.

Prosecutors eventually charged three men in Daniel's murder, one of whom was on pretrial release after being charged only days before with a separate shooting in Brooklyn Park.

But the murder case against the three men began to unravel earlier this year when a key witness changed his testimony. The man previously had told homicide detectives that he had been with the three men before the shooting and had seen them with guns, although he hadn't seen the attack itself, according to a defense filing.

But, when re-interviewed, he reportedly denied even being home when the shooting was said to have occurred. The defense filing said that the man's story had changed several times in the months since the murder. He also told authorities that he made his original statement under coercion by a police investigator, who had threatened to charge him with an unrelated drug case unless he agreed to testify, according to the filing.

While it's rare in first-degree murder cases, local prosecutors are dismissing more cases than in years past for lack of evidence.

From 2015-2020, the Hennepin County Attorney's Office has declined to prosecute 2,868 cases, including 27 murder cases, according to data obtained through a public records request. The number of dismissed cases, the majority of which involved assault allegations, more than doubled in that span, reaching 755 in 2020 — which comes amid a national debate about the role of prosecutors in the criminal justice system.

Mary Moriarty, the former chief Hennepin County public defender, said that inconsistencies by witnesses could make prosecutors reluctant to bring a case to trial, knowing that if a defendant was acquitted, they would lose their ability to prosecute him or her again if new evidence emerged.

The enormous power afforded prosecutors is something that until recently has gone overlooked in the conversation around criminal justice reform, she said.

"There has been frustration for years that (the Hennepin County Attorney's Office) overcharges them, charges cases that should never be charged and then ends up dismissing it after trial date," said Moriarty, who has signaled her intention to run for county attorney. "The goal should be doing whatever's the right thing for the community, for the person who's charged and the person's who's harmed. And what's right for keeping the public safe is very different from what the system has been doing for decades."

Lynch said she doesn't want an innocent person to go to jail. But, she also wants those responsible for her sons' deaths to be brought to justice.

"Two kids murdered on the streets of Minneapolis, and no one's in custody," Lynch said.

In the meantime, Catrice Lynch said she is in the process of launching the Mack Boys foundation, to help the families of victims of unsolved murders, "and to give my sister some type of release."

Libor Jany • 612-673-4064 Twitter: @StribJany