The commission, after the return by the surveyors has been filed with it, shall thoroughly investigate as to the population and wealth proposed to be taken and left by the new county and to that end may send for persons, papers and books giving statistics and may administer oaths, take testimony and employ a stenographer, if deemed by it necessary. It shall make a full report to the Governor of its finding as to the wealth and population embraced within the limits of the proposed new county and as to the wealth and population to be left in each old county to be cut by the new and shall annex to the petition its report with proper exhibits and with any evidence on which the report is based. Forthwith upon the completion of its investigation and report it shall return the petition and such finding and showing as is hereinbefore provided for to the Governor for his information.