Detectives trying to establish whether Peter Tobin is responsible for more killings have released photographs of pieces of jewellery found at his homes.
The 32 items were in Tobin's possession between 1991 and 2006 and have not been claimed by any of his three ex-wives.
It is feared they could be trophies kept from other unknown victims.
Police said they would examine dozens of other unsolved cases after the 63-year-old was convicted of killing Dinah McNichol - his third murder conviction.
Tobin, from Johnstone in Renfrewshire, was jailed for 21 years in 2007 for the rape and murder of 23-year-old Angelika Kluk in Glasgow.
Her body was found bound and gagged beneath the floor of St Patrick's Church, where she worked, in 2006.
The teenagers were found after Tobin was convicted of Angelika's murder
After that trial, police announced plans to question Tobin over the murder of 15-year-old Vicky Hamilton once it emerged that he lived in Bathgate at the time she disappeared in 1991.
When they searched his former home they found evidence, including a dagger, with Vicky's DNA still on it.
Officers found her remains buried alongside Dinah McNicol in the backyard of his former home in Margate, Kent.
Police are now restarting Operation Anagram, tracing Tobin's past movements and examining whether he was responsible for other unsolved crimes.
The investigation will stretch back to the 1960s and police said there were 1,400 lines of inquiry to be followed up across the UK.
Tobin had a nomadic lifestyle, moving frequently, often between the south of England and Scotland, and he is also thought to have used up to 40 aliases.
Police have said they suspect that Tobin had killed before 1991
He is reported to have claimed 48 victims in prison boasts and police are also looking at the possibility that he might be "Bible John", the man thought to be responsible for the deaths of three women in Glasgow in the late 1960s.
Also under scrutiny are the murders of Jessie Earl, who disappeared from Eastbourne in East Sussex in 1980 and who was found dead nine years later, and Louise Kay who disappeared aged 18 from Eastbourne in 1988 and who has never been found.
Det Supt David Swindle, who led the Angelika Kluk murder inquiry for Strathclyde Police, said: "I strongly, strongly suspected and formed the theory that Tobin may have indeed been a serial killer.
"The fact of his age and the method of [Angelika's] killing, and all the other factors surrounding Tobin, made us think this guy's done this before.
"It was also while interviewing relatives of Tobin, that we got indications that Tobin may have been involved in other crimes."