I am not sure the parallelism in the following sentence is right
"Dr.Lattimer, a American physician, attended,observed and spoke on a personal basis with the 22 top Nazi leaders on trial at Neuremberg"
Are observed and spoke together or separate? If together, then no comma; if separate, then you'll need a comma.
Ex: Dr.Lattimer, an American physician, attended, observed, and spoke with on a personal basis the 22 top Nazi leaders on trial at N(e)uremberg.