"investigation of whether" is correct and usable in written English.
You can use it to introduce a clause that describes two or more things being compared in order to determine something. For example: "We conducted an investigation of whether we should expand our operations or not."
Descartes therefore launches an investigation of "whether there is a God, and, if there is, whether he can be a deceiver" (7 36).
The study is part of an investigation of whether the killings amount to genocide.
That was the attorney representing her in an investigation of whether she had abused her power in office.
Still in progress is a federal investigation of whether the school reported sexual offenses as required by the Clery Act.
Mr. Trulock, now the subject of an investigation of whether he disclosed secrets in an unpublished article about the investigation, has said the F.B.I. bungled the investigation.
Cuomo started an investigation of whether the payments were fraudulent because the company knew it did not have the funds to cover them.
Let us hope that the investigation of whether the government corrupted the data to suit its own ends is just as uncompromising.
The chief prosecutor has rejected a demand from the mother of a slain Ukrainian journalist for a criminal investigation of whether top government officials were involved.
The House Judiciary Committee has begun an investigation of whether to impeach him, the only way to remove a federal judge from the bench.
The American Jewish Committee in Berlin has requested an investigation of whether Amazon.de broke German laws by selling Holocaust-denial books.
And that news compounds America's continuing investigation of whether GSK and other drug firms violated the Foreign Corrupt Practices Act, which forbids the bribery of foreign officials.
