Panzermahn -- You asked:
wow, isn't this a forgotten crime by the Allies?
What makes you think it's a crime? What international law or treaty does it violate? Are you sure that this wasn't something every belligerent did, in WWI and WWII and maybe even earlier than that?
You also said:
I didn't knew about this and i would certainly like to find out more about this and perhaps some chapters can be written about this in my book
On 9 Dec 1941 the US Attorney General established the Alien Property Division (APD) of the US Department of Justice to handle certain enemy property responsibilities that resulted from the entry of the United States into the war. An Executive order of 11 Mar 1942 established the WW II Office of Alien Property Custodian (APC) within the Office for Emergency Management (OEM). An Executive order of 21 Apr 1942 transferred the functions, personnel, and property of the APD to the Alien Property Custodian.
An Executive order of 6 Jul 1942 gave the US Secretary of the Treasury authority over foreign-owned properties that constituted general purchasing power and required no active management, such as cash, bullion, bank deposits, and securities. The same order empowered the Alien Property Custodian to take over types of foreign-owned property that were productive resources requiring active management, such as business enterprises, patents, copyrights, trademarks, and ships. An Executive order of 18 Jun 1945, extended the Alien Property Custodian’s jurisdiction over all property of whatever nature in the United States owned by Germany or Japan or nationals of those countries, subject to some limitations.
An Executive order of 14 Oct 1946, terminated the Office of Alien Property Custodian and transferred its functions, funds, personnel, records, and property (except those connected with property in the Philippine Islands) to the US Department of Justice, Office of Alien Property.
Leo T. Crowley was Alien Property Custodian from 1942 to 1944; James E. Markham held the position from 1944 to 1946.
The US also had an Alien Property Custodian in WWI.
You can find the Records of the Office of Alien Property in Record Group 131 (RG 131) of the US National Archives and Records Administration, as part of the US Department of Justice Records.
You might also want to take a look at The Alien Property Custodian: A Legislative Chronological History and Bibliography of the Trading with the Enemy Act, 50 U.S. Code App. 1-40, and the Operations of the Office of Alien Property Custodian, 1917-1952
. U.S. Senate, Committee on the Judiciary (82d Congress, 2d Session).