A defector from North Korea has been mysteriously found dead in a flat with no sign of forced entry.
His heavily bruised body was discovered inside a property Gimhae, South Korea, on Monday.
CCTV footage is now being examined by police to determine how the victim named only as 'Mr A' by local media died.
His body condition, his family say, suggests he may have been attacked or killed at his home.
Investigators noticed a lot of bruising to the man's "face and side" after the gruesome find was made.
An autopsy was carried out and investigators probing his death have indicated the bruising was caused by blood clots that formed after his death.
Police say no external injuries were discovered on the 23-year-old man.
Digital forensics' teams are analysing his mobile phone and CCTV footage to establish if anyone entered the flat which was locked.
The JoongAng reported a "loud" argument was heard before he died and a woman emerged from the victim's flat.
Neighbours also claimed the North Korean man had been seen sporting a "scarred" face last September.
His family have told how he left his former country with his grandmother and father in June 2004 at the age of five.
They travelled on dangerous journey across the Tuman River from North Korea to China, before going on to Mongolia so they would not be detected.
They made their way into South Korea to begin a new life.
The victim is said to have struggled to adjust to his new life and endured bullying from his classmates as he grew up.
He was forced to attend different schools to escape taunts and bullies.
The 23-year-old lived with his grandmother and father while doing a range of jobs in factories and restaurants before he moved out.
Reports claim police found dozens of different medications for the victim who suffered from depression and insomnia.
He was diagnosed with depression and alcoholism three years ago and was being treated, say reports.
His cause of death is unclear, but the mysterious circumstances surrounding his death are similar to other North Korean defectors.
South Korea's Ministry of Unification said: "The government mourns the deceased and is very sorry.
"We are reviewing the overall support system for families in crisis for North Korean refugees.
"The government has made a lot of effort to help North Korean defectors settle down in our society early and stably, but it is true that there are still shortcomings."
The Mirror r eported last week how South Korea's military scrambled dozens of jets after detecting the mobilisation of 180 North Korean warplanes moving near the border between the two countries.
"Our military detected around 180 North Korean warplanes" mobilised in Pyongyang's airspace, Seoul's Joint Chiefs of Staff said.
They said that Seoul "scrambled 80 fighter jets including F-35As" while jets involved in the joint drills were also "maintaining readiness".
There were not any immediate reports of clashes.
