Musk on Saturday gave a $1 million check to an attendee at the rally in Harrisburg, Pennsylvania, which was hosted by America PAC, a political action group the Tesla CEO set up to back Republican Donald Trump in the Nov. 5 presidential election.
Shapiro said on NBC's "Meet the Press" that Musk's plan to give money to registered voters in Pennsylvania is "deeply concerning" and "it's something that law enforcement could take a look at."
The money is the latest example of Musk using his extraordinary wealth to influence the tightly contested presidential race between Trump and his Democratic rival Vice President Kamala Harris. Pennsylvania is a must-win state for both Trump and Harris.
Musk's America PAC is playing a major role in helping mobilize and register voters in battleground states that could decide the election, but there are signs it is having trouble meeting its goals, Reuters was first to report on Friday.
The lucky recipient of Saturday's check was a man named John Dreher, event staff said.
"By the way, John had no idea. So anyway, you're welcome," Musk said as he handed Dreher the check.
On Sunday, Musk handed a second $1 million check to a woman at an event in Pittsburgh, according to a post by America PAC on X.
Musk is promising to give $1 million each day to someone who signs his online petition, which reads: "The First and Second Amendments guarantee freedom of speech and the right to bear arms. By signing below, I am pledging my support for the First and Second Amendments."
To be eligible for the $1 million, petition signers must be a registered voter and live in one of the seven swing states: Arizona, Georgia, Michigan, Nevada, North Carolina, Pennsylvania and Wisconsin, according to the America PAC website.