Three men and a youth have been bailed by police after armed raids during which a woman was kicked to death and a child was held at knifepoint.
Ms Chung was stamped and kicked to death in her own home
Kam Fum Chung, 65, was killed at her west London home early on 6 November.
Later the gang raided a nearby house and threatened a man's daughter with a knife. They fled when the man grabbed their gun and fought back.
Police said the men, two aged 21, one 23 and the other 17, had been released on bail until February 2007.
Police believe the robbers may have targeted Ms Chung, who owned a Chinese restaurant, thinking she had the day's takings with her.
Detectives have established she did not have the money with her when she returned home to Meadowview, Cowley, just before the attack.
A post-mortem examination revealed mother-of-two Ms Chung, who lived alone, died of multiple stamps and kicks to the face and chest.
The gang drove off in her Volkswagen car and forced their way into a house in Vine Lane, Hillingdon, where a man and his two children were asleep.
Wearing balaclavas, one of them brandished a fake gun while another fetched the girl from her room and held a knife to her throat.
But they were forced to escape when the girl's 49-year-old father, grabbed the gun and used it to hit all three of them.
He was stabbed in the knee, but his children were not injured.