A police officer arrested after a man claimed he was paid to kill the officer's wife was released from custody Tuesday and isn't facing charges, authorities said.

Sgt. David Cobb was released after spending 47 1/2 hours in custody because prosecutors refused to authorize charges.

He has known for months that he was being viewed as a suspect in his wife's slaying, said his attorney, Elbert Hatchett.

Police said Cobb, 38, was arrested after Vincent Smothers told investigators he was responsible for at least seven contract killings, including that of Cobb's wife, Rose, 47, who was killed outside a pharmacy the day after Christmas. Smothers and another man were charged Tuesday in Rose Cobb's killing.

A warrant request for David Cobb was denied because it lacked sufficient evidence to charge him, Wayne County Prosecutor Kym Worthy said in a statement.

The only evidence given to the prosecutor's office connecting Cobb to his wife's slaying is the statements of the two men charged in her death, but they can't be compelled to testify, Worthy said.

"There is no admissible evidence upon which to charge him at this time," she said of Cobb.

Police officials believed they had enough evidence to charge one of their own.

"Probably, the only stronger information we could have presented is if we ... were there, eyewitnesses as these people were committing the crime," Assistant Police Chief Robert Dunlap said Tuesday.

On Tuesday, Cobb was back inside the home he had shared with his wife in one of the city's newer subdivisions a few blocks from the banks of the Detroit River. He declined to discuss the case, his arrest or her death.

Cobb was inside the pharmacy when his wife was shot several times through the window of their van.

"The suspicion involved focused on him," Hatchett said. "He has steadfastly insisted that he had nothing to do with his wife's murder.

"We knew they were investigating. We knew what they had and didn't have. They didn't have enough to charge him with a reasonable chance of conviction."

Smothers is charged with first-degree murder in Rose Cobb's death and Marzell Shawn Black, 20, is charged with solicitation of murder, Worthy said.

Smothers, 27, was arraigned Monday on two other slayings committed last June and he was being held without bail.

The prosecutor's office did not know if Smothers or Black had retained attorneys to speak for them.