The son of a master cooper, after attending elementary and continuation school, Wirth learned the sawyer's craft.

During the First World War, at his own request, he served as a non-commissioned officer in the army on the Western front, distinguished himself in battle, was wounded, and was highly decorated.

After the war Wirth returned to Stuttgart in June 1919 and was promoted back to police detective sergeant a short time later.

[4] Wirth was one of the original members of the Nazi Party, joining for the first time in 1923, before it was outlawed briefly in Germany following the unsuccessful Hitler Beer Hall Putsch.

These police officers served as nonmedical supervisors at the killing centers of the euthanasia program, and Wirth was chief among them.

In December 1939 or January 1940, Wirth was present when twenty to thirty German mental patients were subjected to the first known gassing experiment using carbon monoxide.

At Hartheim, Wirth oversaw paperwork as head of the registry office, directed the killing process as the individual responsible for security, and commanded the junior staff as director of personnel.

When four female patients at Hartheim were suspected of having contracted typhus, Wirth shot them to prevent the spread of disease to the staff.

And here it was again this awful verbal crudity: when he spoke about the necessity of this euthanasia operation, he was not speaking in humane or scientific terms, the way Dr. Werner at T-4 had described it to me.

Since Wirth had previous experience in murdering with gas in the "involuntary euthanasia" program, Globocnik appointed him as the commandant of Bełżec in December 1941.

Before coming to Belzec, Wirth became acquainted with the gas vans in operation in Chełmno and in the eastern occupied territories of the Soviet Union and learned their advantages and disadvantages.

Wirth preferred to set up a self-contained extermination system, based on an ordinary car engine and easily available gasoline and not dependent on supply by outside factors...Wirth carried out experiments to determine the most efficient method of handling the transports of Jews from the time of their arrival at the camp until their murder and burial.

The basic structure of the camp and the various actions the victims were made to do as soon as they left the train were intended to ensure that they would not grasp the fact that they had been brought for extermination.

Wirth's official title in this capacity was Abteilung Reinhard – Der Inspekteur des SS-Sonderkommandos beim SS- und Polizeiführer Lublin.

[13]During the construction of Sobibór, the second Aktion Reinhard camp, Wirth visited the incomplete site, and conducted an experimental gassing of 25 Jewish slave-labourers.

When Treblinka (the last and most efficient Reinhard camp) was set up, Wirth took a direct role in reorganizing it when the first Commandant, Dr. Irmfried Eberl, was replaced by Franz Stangl.

Stangl recalled one of Wirth's inspection visits to Treblinka as Inspector of Operation Reinhard, around September 1942: To tell the truth, one did become used to it... they were cargo.

[5] On 3 November 1943, after the Sobibór uprising, SS and police units shot all of the Jewish labor forces still incarcerated at Trawniki, Poniatowa, and Majdanek concentration camps during Aktion Erntefest ("Operation Harvest Festival"); 42,000 prisoners in all.

From autumn 1943, Wirth's role was to oversee the Risiera di San Sabba concentration camp as well as to combat partisans over the border in occupied Yugoslavia.

He commanded SS Task Force R, which engaged in antipartisan and anti-Jewish actions in the Trieste-Fiume-Udine area of northern Italy.

[10]: 399 Allegedly to remove potential future witnesses, their superiors assigned former death camp staff to the most dangerous job they could find: anti-partisan combat.

"[14] Wirth was shot and killed on May 26, 1944 by Yugoslav Partisans while travelling in an open-topped car near Kozina, Istria while on an official trip to Fiume.

In 1959, his remains were transferred to the block 15, tomb 716 of the German Military Cemetery at Costermano, near Lake Garda, northern Italy.