The National Crime Agency and Crimestoppers have released these images in the hope of catching murder suspects involved in crimes committed as far back as 20 years ago.
One suspect is believed to have fled the country, and a reward of up to £35,000 is being offered for information leading to his arrest and return to the UK.
If you recognise any of these men, please contact the National Crime Agency at 0370 496 7622 or Crimestoppers at 0800 555 111.
1. Derek McGraw Ferguson
Ferguson is sought in connection with the murder of Thomas Cameron on 28 June 2007 at the Auchinairn Tavern, Bishopbriggs near Glasgow. | National Crime Agency
2. Kevin Thomas
Kevin Thomas Parle is wanted in connection with the murders in Liverpool of 16yr old Liam Kelly in 2004 & Lucy Hargreaves in 2005 | National Crime Agency
3. Allan James Foster
Allan James Foster is wanted for the murder of South Shields man David "Noody" Rice who was shot several times as he sat in his car on May 24, 2006. | Crimestoppers
4. Waijs Dahir
Waijs Dahir left Northampton immediately and is believed to have fled the country after Jon James Casey was killed on January 16, 2015. A reward of up to £35,000 is available for information given to Crimestoppers leading to the arrest - and safe return to the UK. | Crimestoppers