Why was Eagan disturbed by the Loan Sharking Investigation?

The letter above was sent to a police officer working for Sheriff Mel Colman by State Attorney Robert Eagan. Why does Eagan appear to be more concerned about stopping the investigation of loan sharking than getting to the truth about the murder of four people?  Was Eagan trying to insure that the real motive for the murders by people who wanted to stop Zeigler from exposing the loan sharks would not be discovered? Why didn't Eagan go to the sheriff instead of bypassing him?

State Attorney Robert Eagan, shown here in 2001, never subtyped the blood found on Zeigler's shirt or on Charlie Mays' pants even though he knew that Mays and Perry Edwards who were both found dead in the store had the same blood type. In his closing argument before the jury, Eagan demonstated to the jury how Zeigler had supposedly gotten Perry Edwards' blood on his shirt as he held him in a head lock and beat his head with a metal linoleum crank.  He also led the jury to believe that the blood on  Charlie Mays was his own blood since Mays had been shot in the abdomen and then also was beaten to death with the same metal crank. The DNA tests finally proved Eagan to be completely wrong. It showed that the blood on Zeigler's shirt came from Charlie Mays whom Zeigler had fought off after Mays jumped him, and the blood of Perry Edwards was saturating May's pants. Since Mays was killed after Perry Edwards' blood had dried, Mays must have been one of the killers as Zeigler always claimed.

2008 Citizens Committee for Justice for Tommy Zeigler   www.freetommyz.com