One hundred people, whose DNA shows connections to a dead baby found abandoned in Bolton, "may be related" according to police.
Detective Inspector Aaron Duggan says officers will rank the matches according to their "proximity" to the town.
More top news
Cold overnight with frost and ice risk. Sunshine and showers Friday
Violence flared on the streets of Liverpool on Wednesday night as dozens of men clashed in a brawl that saw chairs and missiles thrown.
Convicted killer Venables has been returned to prison after he was caught with child abuse images for a second time and arrested last week.