The two Russian soldiers first talk to two unarmed civilian men at a car company outside Kyiv.
When the men then turn around, the soldiers fire several shots - in the back.
They both fall to the ground.
The surveillance video, first published by CNN, is said to be from March 16.
The victims have been identified.
One of them is the owner of the vehicle company.
The other is a 68-year-old guard employed by the company.
His daughter has spoken to CNN.
She can not watch the video, she tells CNN.
- They are executioners.
It's awful, my father was a peaceful and unarmed 68-year-old man, she says.
Can be used as evidence
On Tuesday, the International Criminal Court in The Hague, ICC, sent 42 experts to Ukraine.
The team largely consists of investigators and forensic scientists from the Netherlands.
The field effort is said to be the largest ever made by the ICC.
The incident at the car company in Kyiv on March 16 may be used as evidence in a possible trial.
But it can be difficult to hold someone accountable, according to Jann Kleffner, professor of international law at the Swedish National Defense College.
- In normal cases, you must have the persons in custody in order to be able to prosecute them, even if it is not necessarily a requirement to investigate the incident itself.
We do not know where these people are.
If they are under Russian control, it is highly unlikely that they will be prosecuted in Russia.
The perpetrators' superiors may also be held liable.
- We have an important principle in international criminal law and humanitarian law.
It means that a military commander can be held responsible if crimes are committed by armed forces under his or her command.
First soldier to trial
Ukrainian prosecutors say they have identified thousands of cases of suspected war crimes.
Recently, a 21-year-old prisoner of war, belonging to a Russian armored division, was brought to justice in Kyiv after the murder of a 62-year-old civilian.
Russia's Defense Ministry has denied attacks on civilian targets.