Efraim Zuroff, the chief Nazi hunter with the Simon Wiesenthal Centre, has welcomed the arrest of Hans Lipschis over allegations he served as a Auschwitz death camp guard.
Lipschis number 4 on his current list of "most wanted Nazi war criminals".
Mr Zuroff told the Associated Press: "This is a very positive step, we welcome the arrest. I hope this will only be the first of many arrests, trials and convictions of death camp guards".
More top news
WARNING: Some people may find some of the images in this report distressing.
Medical staff who helped during the Westminster terror attack have received a royal thanks for their life-saving efforts.
Colin Gregg, the son of the founder of the Greggs bakers chain, has been jailed at Newcastle Crown Court for 13 and a half years.