Authorities named a suspect Monday in the brutal killings of four children in the 1970s, raising hopes of solving a case that terrorized the region.

Theodore Lamborgine, 65, is "our most promising suspect at this particular time," Wayne County Prosecutor Kym Worthy said at a news conference in Detroit.

The admission that Lamborgine is a suspect in the recently revived "Oakland County Child Killer" case came as Worthy announced charges against Lamborgine in an unrelated series of sexual assaults against six children in the 1970s and 1980s.

Lamborgine, whose home was listed as Parma Heights, Ohio, pleaded not guilty to four counts of first-degree, one count of second-degree and 12 counts of third-degree criminal sexual conduct Monday afternoon. He was ordered jailed without bond.

Worthy's office also is bringing charges against Richard Lawson, a convicted murderer, in the sexual assaults of eight juveniles from several Detroit-area communities during the same time period. Lawson, 60, faces 28 counts of criminal sexual conduct but is not a suspect in the child killings.

The two men knew each other and worked together as sexual predators, Worthy said.

"We do consider this a sex ring of sorts," she added, saying authorities believe there are "many, many more" victims.

The two lured their victims, some under 13, to motel rooms and homes with soft drinks, drugs, food and cash, Worthy said.

"These suspects knew that there were a lot of kids living in that area -- a lot of poor kids living in that area," said Livonia police Detective Sgt. Cory Williams. "It didn't take too much for them, the suspects, to figure out they could take the kids a case of pop, some drugs or cash."

Lawson, while not a suspect in the killings, provided authorities with information about Lamborgine related to the case, said Garry Gray, head of the Oakland County Child Killer Task Force.

The four slain children -- Timothy King, 11; Mark Stebbins, 12; Jill Robinson, 12; and Kristine Mihelich, 10 -- were suffocated between February 1976 and March 1977.

Each child was missing between three days and nearly three weeks before the body was found. Two had been raped, and one had been shot in the face with a shotgun.

Authorities revived the investigation into the unsolved killings in February 2005, saying they would begin reanalyzing evidence and leads using more advanced computer databases and forensic techniques.

The investigation's last big lead had fallen apart in 2000, when DNA from the exhumed body of a suspect failed to match the genetic material in a hair found on one of the victims.

Worthy said the sexual assault charges are the result of a two-year investigation. The alleged victims were identified with help of the multi-jurisdictional Oakland County Child Killer Task Force.

Lamborgine and Lawson face maximum penalties of life in prison if convicted of the sexual assaults.

Lamborgine was not represented by an attorney at his court appearance Wednesday. Court officials told him one would be appointed for him.

Lawson is behind bars in Michigan. He was convicted of murder and armed robbery in March in the 1989 death of Exavor Giller, 67, who owned a cab company where Lawson once worked.