Father Leo. J. Walter was a Maryknoll missionary. He was ordained on 22 June 1941 and assigned to Kweilin (Guilin), China. He and his group of newly ordained priests had arrived in Hong Kong just before the Japanese invasion and became trapped in the city and not able to proceed to their inland missions.
After the fall of Hong Kong, he was interned at Stanley Camp. In September 1942, he was released from confinement (see here) and later gained permission from the Japanese authorities to enter China and proceed to the inland mission at Kweilin. Father Walter and a group of Maryknoll priests left Hong Kong in January 1943 and safely reached Kweilin on 2 February 1943.
Father Walter would go on to serve the Maryknoll missions in China until 1950. He was reassigned to the Philippines the following year.
Source
1. Maryknoll Mission Archives: https://maryknollmissionarchives.org/deceased-fathers-bro/father-leo-j-walter-mm/
2. Catholic News Service - Newsfeeds dated 23 June 1941. See here
3. Brooklyn Daily Eagle dated 5 February 1943. See here
4. The Shanghai Evening Post and Mercury dated 5 February 1943. See here