A baby monkey that was stolen from Blackpool Zoo is still missing after four others that were taken were found in Brighouse.
Police officers were called to an address on Brookfoot Lane on Saturday May 3 after the monkeys were left on a doorstep.
Two female and one baby cotton-top tamarins and two male emperor tamarins were taken by thieves who broke into their enclosures at the zoo on April 29.
Chief Inspector Ian Croft, of Halifax District Police, said: “At 9.24pm on Friday, May 2, officers were called to an address in Brookfoot Lane, Brighouse, where they found four tamarin monkeys, which were believed to have been stolen from Blackpool Zoo.
“Officers contacted the zoo, who came and collected the animals from Halifax Police Station.
“We are now helping Lancashire Police with their enquiries to try and trace the outstanding monkey, a three-month old baby cotton top tamarin, and would like to speak to anyone who saw anything suspicious in the Brookfoot Lane area of Brighouse at around 9pm last night.
“Anyone with information is asked to contact police on 101.”
The burglary happened overnight between April 29 and April 30 when offenders cut a hole in the perimeter fence and approached two separate monkey enclosures.
They then removed the locks and took monkeys from each enclosure.
The monkeys, which are a critically endangered species, can fetch up to thousands of pounds on the black market in the UK and abroad.