Police in the western city of Cologne warned residents Sunday to be on the lookout for a mentally ill murderer who had escaped his psychiatric ward.

Officials granted the man, Otto Krüger, permission to temporarily leave the ward at 1:45 p.m. local time (1245 UTC), but he failed to return to the facility at the agreed-upon time.

Police said Krüger could be anywhere between the cities of Cologne and Bonn. He is known to have used public transport in the area in the past.

Officials posted Krüger's photo and a full description of his attire, asking citizens to contact police if they see him.

But police warned residents not to approach him. He is dependent on medication and could be very aggressive, especially if he has been drinking alcohol.

The 67-year-old went missing once before in 2014. He was then placed in a closed psychiatric ward in 1999, after he kicked his 78-year-old neighbor to death a year earlier in the town of Bad Godesberg, south of Bonn.

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