Danny Lee execution. Why a federal crime?

Danny Lee was executed by federal authorities for the murder of an Arkansas family. How were the murders a federal crime?

Murder in aid of racketeering. That makes it a Federal crime.

How was he in a racket?

A jury convicted Daniel Lewis Lee of conspiring to violate and violating the Racketeer Influenced and Corrupt Organizations (RICO) statute, 18 U.S.C. §§ 1962© and (d), and of three murders in aid of racketeering in violation of 18 U.S.C. § 1959. The jury also returned a verdict of death and a death sentence was imposed.

United States vs Lee.

From here - https://caselaw.findlaw.com/us-8th-circuit/1344687.html

Thanks, Duckster.

And, by the way, Jesus Christ he deserved it.