Instead, he charges, they were allowed to go free because of "persistent" and "intense" pressure from the American president of the tribunal, the Danish newspaper BT reported Thursday.
In a confidential letter dated June 6, Danish Judge Frederik Harhoff said the acquittals "have occasioned deep professional and moral dilemmas for me."
He adds, "The worst of it is the suspicion that some of my colleagues have been exposed to short-term political pressure and this completely changes the premises of my work to serve the principles of justice and reason."
He singled out ICTY President Theodor Meron as pressuring fellow judges to acquit those charged with executing civilians and ethnic cleansing, among other crimes.
"It would seem," Harhoff wrote in a five-page letter, that countries such as Israel and the United States "felt that the tribunal was getting too close to top-ranking military commands."
The judge cited the 2011 reversal, by a 3-2 vote of an ICTY appellate court, of the convictions of two Croatian generals for crimes against humanity. The same court, by the same 3-2 vote, released a Serbian general in 2012 who had been sentenced to 27 years in prison.
Harhoff predicted the precedent set by the appeals court "will in future and in the majority of cases allow the top-ranking person to go free."
Several judges have complained Meron pressured them to issue opinions before they were ready, The New York Times reported.
Meron had been expected to be re-elected tribunal president for the fall session, but 18 judges have said they favor an alternative candidate.