Walter A. Kostecki was born on March 6, 1911 in Boston, Massachusetts. He graduated from Tufts College with a Bachelor of Science degree in chemistry in June 1933 and went on to earn an M.D. from George Washington University School of Medicine in Washington, D.C. in June 1937. He married Mary Louise Sullivan, an Irish nurse, in 1940, and they would have two daughters and one son.
Kostecki went on active duty in the Army Medical Corps on November 1, 1939 and served within the United States until he was transferred to the Philippines on January 24, 1941. He arrived at Manila on February 20 and was stationed at Sternberg General Hospital in Manila as a ward surgeon until March 6. He then served as an assistant flight surgeon at Nichols field from March 6 to August 1, 1941 and afterward as a surgeon with the 45th Infantry Regiment of the Philippine Scouts. He served as an assistant regimental surgeon and battalion surgeon, treating illnesses and diagnosing surgical conditions.
During the Battle of Bataan, Kostecki also provided emergency surgical and medical treatment. He was captured on April 7, 1942, two days before the fall of Bataan, by a Japanese Infantry unit, which forced him to serve as a cargador until the Death March began. He was a captain at this time. He was interned first at Camp O'Donnell and then at Cabanatuan from January 24 to February 23, 1943. From there he was sent with 200 other medical men to Japan, where he was held at Fukuoka Camp No. 1 on Kyushu Island from March 17, 1944 to April 17, 1944, at which time he was taken to an airport a few miles from Fukuoka. On January 19, 1945 he was taken to another camp, also called Fukuoka Camp No. 1, located in a grove of pine trees. Ten days later, another group of American POWs, 195 in number, were brought in from a hellship, most likely the Brazil Maru. One of the men was then-lieutenant colonel Harold K. Johnson, who would later become a General and Army chief of staff.
Kostecki held a lottery to determine which men would receive the small supply of intravenous feeding units by having the men draw from a Japanese soldier's fatigue cap. Johnson was one of the lucky ones, and he was also one of five men who shared a can of meat which Kostecki had sequestered away from a Red Cross package. Among the group of 195, 50 died, and the rest were sent to Korea in April 1945. Kostecki remained at Fukuoka to care for the sick.
Throughout his imprisonment, Kostecki was not allowed to keep any medical records, and he was forced to sign prisoners' death certificates, which had been made out by the Japanese. Many of the deaths were due to malnutrition, pneumonia, dysentery, and beatings. Kostecki worked as a doctor in the camp hospital, which had no beds and poor ventilation. The camp doctors secretly paid a Japanese medical orderly, Masato Hata, to obtain needed medicines, and Kostecki himself paid Hata to fill prescriptions more quickly.
After the war ended, Kostecki spent six months recuperating in a hospital at Fort Devens, Massachusetts. He chose to stay in the Army, serving at Fort Sam Houston in Texas and at Fort Benning in Georgia, because of the strong impression of endurance and heroism that he witnessed among the servicemen who were prisoners of war. Then in 1959 he was stationed at Fort Myer, Virginia as a post surgeon and director of the Andrew Rader Army Clinic as well as surgeon to the Inter-American Defense Board; he remained in these capacities until his retirement in 1971. During his career, he earned the Legion of Merit, the Bronze Star, two Purple Hearts, and two Army Commendation Medals. Following his retirement, he moved to Halifax, Massachusetts and continued to practice medicine until 1980.