Author James Rusbridger examined the records of the 6th Heavy Bomber Group operations while in Panama. The records show the sinking of a large submarine the morning of 19 February 1942. Since no German submarine was lost in the area on that date, it is assumed the large submarine was the Free-French "Surcouf", which was the largest submarine in the world at the time. Rusbridger suggested that a collision reported by the American freighter Thompson Lykes on the night of 18 February, sustained damaged to the submarine's radio antenna with the stricken vessel limping towards Panama.