The son of Paul Müller, an architect, and his wife Wilhelmine, Siegfried Müller was born on the 18th of October 1914 in Krefeld on the Rhine. His father served in the Kaiser's Army during the first World War and was killed in action at Verdun in May 1916. At the time of his fathers death Müller was not yet two years old. In 1920 his mother remarried, Mr. Heinrich Becker, a locksmith. Müller attended Volkschule in Krefeld from Easter of 1922 until the Easter of 1927 and then Mittelschule in Essen-Altstadt, which he completed in 1933 with the mittlern Reife. Following this he worked with an architect in Essen-Bredeney as an apprentence "bautechnischer".

Müller decided to forego his architectual training to join the Heer. On the 27th of October 1935, a few days older then 21, a big man standing over 6' tall (185 cm.), Müller joined the 1.Kompanie of Pionier-Bataillon 1 stationed in Königsberg. He recieved his basic training in Königsberg and later attended a course for officers there, finally commissioned with the rank of Leutnant der Reserve on the 18th of January 1938. The next day he was given command of 3.(mot.)/Pi.Btl. 1. He remained in this post until his transfer to the SS as an active officer on the 1st of November 1938. In the meanwhile Müller had joined the SS (# 230 815) on the 1st of April 1934.

Müller was assigned to SS-Totenkopf-Standarte "Brandenberg" as a SS-Untersturmführer.

After the 227. Volks.Gren.Div. was unsuccessful in forcing a breakthrough through the enemy positions to the west of Hollerath on 16.12.44, on the morning of 17.12.44 the SS-Pz.Gren.Rgt 25 was given the order to force the breakthrough towards Krinkelt over the troops that were bogged down in the attack.

Even though the moment of surprise had already been lost and the enemy had thrown the 2nd American Infantry-Division into the area of Rocherath - Krinkelt, in two days of the hardest fighting through village and forest the Regiment succeeded to breakthrough the positions of the 99th American Infantry-Division, to take Rocherath, stubbornly defended by the 2nd American Infantry-Division, and to force the enemy into abandoning Krinkelt. Over 450 prisoners were brought in, the number of dead and wounded that the enemy left behind on the battle field was even higher.

This success, crucial for the entire conduct of the operation, is primarily attributed to SS-Sturmbannführer Müller, who's personal involvement repeatedly determined the outcome of the battle, with the extraordinary difficulties in command it presented during the fighting in the streets and woods³.

Müller was an architect after the war. He died in Hamburg on the 7th of April 1974, aged 59, under the assumed name Heuser⁴.