But police say both are equally capable of being solved, even though detectives have run into dead-ends on both investigations.
"You never know when someone's going to come forward with something," said Pomona police Detective Jennifer Turpin.
Police this week said they hope to revive interest in the 2006 fatal shooting of 24-year-old Andre Laurent of San Dimas and the 1973 killing of Arthur Martinez. A $50,000 reward has been posted for an arrest in the Martinez case and $85,000 in rewards has been offered in the Laurent case.
It is tenacious family members who prompted Pomona police to focus on the cases, Turpin said.
Some relatives regularly contact detectives to see if they've made any progress on making an arrest.
In Martinez's case, his nephew, Andrew Castro, is motivated by the age of Martinez's elderly mother.
"He wants it solved before she passes away," Turpin said.
Martinez was killed Feb. 16 and his body was dumped in the San Antonio flood control channel at Phillips Drive west of East End Avenue.
Detectives have exhausted all leads in the case, but police say many people who knew Martinez still live in the area.
"We have our eyes on some people, but basically because it's so old, there's not going to be any DNA evidence," Turpin said. "It's going to take that key witness to come forward."
Laurent was killed Jan. 4, 2006 at an ampm minimart in the 2400
Two men in a Chevy S-10 Blazer drove up to Laurent and one of them said something. When he approached the vehicle to hear what the man was saying, they got into a short conversation and he was shot.
Police say both men had been thrown out of the Strip Joint in the 1400 block of East Mission Boulevard before the shooting.
They fired at a security guard and a patron of the club, but the bullets hit the building instead.
Investigators have identified possible suspects in the case, but don't have enough evidence to make an arrest.
"It's one of those cases that we just need the last piece of the puzzle," Turpin said.
Turpin said the passage of time doesn't always decrease the chances of solving a case.
She's currently following up leads generated from a homicide witness who came forward around Christmas with information in a 1990 case. In that case, the holidays motivated the witness to call.
Holidays, anniversaries of a killing and birthdays of victims often stir up people who were too apprehensive to come forward previously.
Turpin even received leads from an out-of-state caller a couple years ago on a 1981 cold case. No arrest has been made in that case, but she says she's making progress.
She says the same situation could happen with the Martinez and Laurent cases.
Anyone with information may call Turpin at 909-620-2169.
Reach Melissa via email or call her at 909-386-3878.
Get the latest crime and public safety news on Twitter @IECrime.