Officer Byrne was killed on a February night half a block from her house.

The police are still seeking the murder weapon in Officer Byrne's killing.

It was still uncertain yesterday who fired the three bullets that struck Officer Byrne.

Four men have been arrested and charged with Officer Byrne's murder.

Police sources have not ruled out that one or both men could have been involved in Officer Byrne's shooting.

Officer Byrne died instantly when an assailant fired five shots through the driver's side of the radio car.

Prosecutors say Officer Byrne was killed by four men at the order of a drug dealer seeking retaliation against the police.

"I came here to say thank you and to help keep the memory alive," Officer Byrne said.

Because of Officer Byrne's slaying, he said, the officers working in the drug force "have been told to stick together" and use caution.

"He had six more months than I did on the job," she said of Officer Byrne.