The case attracted worldwide media attention when Redford halted production of "The Natural," being filmed on location in Buffalo, N.Y., and came to Boulder for Wells' funeral.
Wells and Redford's daughter Shauna, then 22, were both students at the University of Colorado and lived in the same building.
Police suspected Smika, Wells' roommate, and arrested him a few months after investigators said they linked him to the murder. Smika was never prosecuted because the district attorney at the time declined to take the case.
Smika left the area, and in 1986 his abandoned car was found in Beverly Hills, Calif.
Wells' mother, June Menger, said Thursday that Boulder investigators have been dogged in their work to solve the case.
She isn't bitter about the delays in getting a murder warrant. She said prosecutors at the time of the killing lacked the evidence techniques that have since allowed detectives to link shotgun pellets recovered from Wells' body to shells found at the Smika family residence in Akron.
Menger said Robert Redford and her son were friends, and went jogging and skiing together.
She said Redford initially decided not to attend the funeral, worried it would become a media circus. But he decided to come anyway because of his close friendship with Wells. "He said it had turned into his nightmare too," she said.
Robert Redford said in 1997 that Wells' murder still haunted him.
"It's like a partially opened door with a very dark room behind it," he said.
In 2010, the Boulder County District Attorney's Office agreed to review the case and approved an arrest affidavit for Smika. But authorities could not find him. Smika's bail was set at $5 million after the warrant was issued.
"It's past time for justice for Sid Wells and his family," said Boulder Deputy Police Chief Dave Hayes, one of the first detectives to investigate the case.
"Thayne Smika escaped a first-degree murder charge, and has likely been living a life of freedom while the Wells family has been grieving for three decades," he said a statement Wednesday.
Police said Smika has been at large since he disappeared from the Boulder area in 1986 and that he might have fled the country.
Smika, who was often late with rent, was supposed to pay Wells that afternoon, investigators said.