Police this week released photos of two similar attacks at Berlin U-Bahn stations in which victims were pushed down either stairs or an escalator.

Photos released on Tuesday depict the 38-year-old victim at the tourist hub of Alexanderplatz falling down a flight of stairs. Police say that on June 11th, an unknown man hit the victim in the head from behind, causing him to fall down the stairs, with his head hitting the metal handrail multiple times.

Police note that there are no indications that the two men knew each other.

As the man fell down the stairs, the perpetrator stood above and watched.

“To see this is always upsetting,” said a police spokeswoman.

As a result, the victim sustained a serious head injury and numerous bruises all over his body, which had to be treated in hospital.

The perpetrator’s face and Chicago Bulls basketball jacket were captured relatively clearly by the security cameras, and police are hoping the release of the images will help them catch him.

“We are optimistic that we will get him,” said the spokeswoman.

Within just a few hours of publishing the photos, police had already received two tips.

Unlike in the high-profile “U-Bahn kicker” case from last October, police decided not to release the full video. Video material is only supposed to be released when all other police search methods have been exhausted.

The footage of last year’s case, depicting a man kicking an unsuspecting woman down the Hermannstrasse U-Bahn station’s stairs, sent shockwaves across Germany and beyond.

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The perpetrator was ultimately found after the video was released, and last week sentenced to nearly three years in jail.

On Monday, police also released photos to help find two men behind an attack at the Gesundbrunnen U-Bahn station against three other men aged between 20 and 23. This attack took place in January.

Police say three victims were standing on the downward escalator when they heard a loud shout, turned around and saw the duo. One of the perpetrators clung to the handrails while he swung his legs out and kicked the 20-year-old man, who then fell down the moving stairs.

The pair then targeted the 23-year-old, kicking him in the upper body and face. They also reportedly choked the third man, 22, before fleeing. The first two were slightly injured, while the third man remained unharmed.