Your assumption is wrong
Grand juries are selected at random from citizens residing in the relevant district.
For Kentucky specifically:
The Administrative Office of the Courts compiles a county-by-county master list of prospective jurors for the entire state. The master list includes all people filing a Kentucky resident individual tax return, in addition to registered voters and licensed drivers over the age of 18.
So, the random selection pool is limited to taxpayers, voters and drivers but selection from that pool is random. Further,
To qualify for jury service, a person must:
-Be 18 years of age or older.
-Be a United States citizen.
-Be a resident of the county in which the case is to be tried.
-Be able to speak and understand English.
-Not have been convicted of a felony, unless pardoned or had his or her civil rights restored by the governor or other authorized person of the jurisdiction in which he or she was convicted.
-Not be currently under indictment.
-Not have served on a jury within the past 24 months.