He was arrested not long after World War II began and the Gestapo moved him to several concentration camps before sending him to Dachau where he died from disease.

On 10 January 1940 he was sent to the concentration camp at Stutthof and then later on 6 April to Grenzdorf and Sachsenhausen before being sent to Dachau as his final destination on 13 December 1940.

But before that the prisoner Stanisław Bieniek made a death mask and a cast of the late priest's right hand.

[2] The beatification cause started in a diocesan process spanning from 1964 until closure on 18 February 1995 at which point the Congregation for the Causes of Saints validated it in Rome on 12 May 1995.

Pope John Paul II approved his beatification on 26 March 1999 after confirming that Frelichowski died "in odium fidei" ("in hatred of the faith") and so beatified him later while in Poland on 7 June 1999.

On 22 March 2002 he was made the patron for Polish scouts after the Congregation for Divine Worship and the Discipline of the Sacraments approved the request that had been lodged in 1999.