Heinrichsohn was drafted in 1939 after graduation for military service but was dismissed as unfit. He began to study law, but was assigned in the Reich Main Security Office. He was established in September 1940 as an officer cadet Employees of the Jewish section of the German Security Police in France under Theodor Dannecker, his immediate superior was then Heinz Röthke. From 1943, he was an employee of the commander of the Sipo Kurt Lischka. In 1942, Heinrichsohn was commissioned at subordinate rank of SS-Unterscharführer (NCO) in the capacity of transport clerk the deportation of tens of thousands of stateless and French Jews to Auschwitz. Complementing a recording of a meeting that he had with the French prefect Jean Leguay, Heinrichsohn noted: "On Friday, 28. 8. 1942, 25000 Jews have been deported." At this meeting, Heinrichsohn listed also that the arrests of the "September Programme" jointly "police, gendarmerie and Wehrmacht" were carried out. When it came to delays in transit on September 30, 1942, Heinrichsohn oversaw the regular exit from the Drancy internment camp, including French Senator Pierre Masse deported to Auschwitz-Birkenau. For transporting no. 45, on 11 November 1942, Heinrichsohn had 35 bedridden elderly people selected from the Hôpital Rothschild, to increase the number of deportees.
After World War II, Heinrichsohn studied law in Würzburg. He was unknown neither about internment nor denazification. He settled as a lawyer in Miltenberg and was elected in 1952 as a CSU member for the second, honorary mayor of his residential community Bürgstadt, where in 1946, he married his wife. After 1960, he was also part-time, there first mayor and he gained a reputation of the town residents, because it prevented the incorporation. He was also a deputy in the Miltenberg council.
On March 7, 1956, he was convicted to death in France in absentia. As a prosecution (and conviction) by the Allies formally prevented a prosecution in the Federal Republic of Germany, it took until 1975 until this process obstacle to the reconciliation agreement in 1971, against the resistance of the FDP politician Ernst Achenbach, could be eliminated. When in 1976 on the initiative of the French historian and Holocaust survivor Serge Klarsfeld, his involvement became known in the Holocaust, he gave the council a statement, that the France Gestapo agent named "Heinrichson" was not identical. This affidavit worked not only in the community but also the board of the CSU, whose Secretary General Edmund Stoiber did not want to interfere or prejudice a pending investigation. Even before the trial Heinrichsohn was in 1978 re-elected with 85% of votes and without opposition as SPD mayor. Iin 1977, Klarsfeld published by incriminating documents which the Oberlandesgericht Bamberg did not recognize, and did not want to withdraw Heinrichsohn's admission to the bar. In June 1978, Serge Klarsfeld organized a political demonstration of about eighty French in Miltenberg.
In 1979, Heinrichsohn was indicted along with Lischka and Herbert Hagen "to have made to the intentional and unlawful, cruel, insidious and committed for base motives and homicidal intent". The indictment was based, inter alia, on a book authored by Wolfgang Scheffler. Röthke was passed in 1965, unmolested, although also sentenced in France to death. Serge Klarsfeld had put together a collection of documents on behalf of the plaintiffs from those found in Paris Gestapo files, from, inter alia, Heinrichsohns involvement in the deportation of Greek Jews and the deportation of Jewish children emerged from France. Heinrich son lawyer Richard Huth however, had the Romanian-born Jews, Serge Klarsfeld denied the right to speak for the French Jews. Heinrichsohn had declared in court that he lacked a sense of guilt, because it was not until after the war that he knew of the Jews' murder; he had divided Jews only to work assignments. Heinrichsohn however, was identified by witnesses; it was detected that he had small children and sick deported, and the historian and Holocaust survivor Georges Wellers could describe as a witness of a 1946 writing about the conditions in Drancy, during Heinrichsohn's tenure. Dannecker after a joint tour of duty on July 20, 1942, in writing about the detained and initialed by Lischka, made the assessment that the: "end of Jews' destruction are approaching", had been well known to him.
On February 11, 1980, Heinrichsohn was sentenced by Circuit Court Cologne to six years in prison, Lischka to ten, Hagen to twelve years. Bürgstadts residents had organized during the process behind their mayor and collected the $200,000 bail, with whom he was living at large during the process audit; however, he was arrested in March 1980 because of the flight risk. On July 16, 1981, the Federal Court upheld the verdicts. On June 3, 1982, he was released early by decision of the Oberlandesgericht Bamberg, after the Landgericht Bayreuth had this rejected in March 1982 as the two-thirds limit had not yet expired. In 1987, the rest of his sentence had passed. Heinrichsohn showed no guilt and even withdrew a perjury, because he remained in the trial of Modest Graf von Korff in his testimony that he knew nothing about the murder of Jews. He eventually lived with his new wife in a neighboring Bürgstadts.
The opening of the trial in Cologne was for Serge Klarsfeld and his wife Beate Klarsfeld a later success in their efforts to bring the German and French Holocaust perpetrators to justice. The relatively heavy prison sentences for the defendants was a novelty in the case-law of the Federal Republic of Germany.
Bürgstadt's residents were convinced of the innocence of their fellow citizen, which journalist Lea Rosh documented in statements in several television features for Kennzeichen D.