A ceremony was held in a Shenyang cemetery before this year's Martyrs' Day on Sept 30 to identify six soldiers who died in the 1950-53 War to Resist US Aggression and Aid Korea.

It's the first time that unknown martyrs from the Chinese People's Volunteers have been identified by DNA technology and also for the first time, a database was set up containing remains of CPV martyrs and their relatives' DNA, Science and Technology Daily reported.

The mission to identify unknown martyrs was conducted by a team led by Wang Shengqi, a researcher with the medical research institute under the Academy of Military Sciences of the Chinese People's Liberation Army.

The team has solved two difficult problems. One is to extract valid DNA from the remains. Having been buried or exposed to the sun for a long time, and corroded by microorganisms, the remains posed a challenge for the team to extract valid DNA. The normal technique is time-consuming, costly and the success rate is low. The team found a new method to extract DNA efficiently.

The other difficulty is the identification. Most soldiers died at a young age. They had no offspring and their parents and siblings are seldom alive, as it has been nearly 70 years since they died. The team used distant relatives' DNA for matching and adopted a new sequencing technique.

Since 2014, the remains of 599 soldiers have been sent back to China from the Republic of Korea. Wang's team has finished DNA analysis of 494 remains.

During the War to Resist US Aggression and Aid Korea, the Chinese People's Volunteers fought alongside the Korean People's Army and tens of thousands of CPV soldiers died.