CHICAGO (Reuters) - Wisconsin prosecutors filed a four-count criminal complaint on Thursday against a 26-year-old woman, charging her with sending e-mail threats to Republican state senators after they passed controversial curbs on public employee union rights.

Katherine R. Windels, of Cross Plains, Wisconsin faces a maximum penalty of three and a half years in state prison on each of the two most serious charges -- both felonies -- that she threatened to destroy property with explosives.

In addition, Windels is charged with two counts of using a computer to send a message threatening harm or injury, misdemeanors that each carry a maximum penalty of 90 days in prison. She also faces as much as $22,000 in fines.

According to the complaint, which was filed in Dane County Criminal Court, Windels sent two e-mails on March 9 to 16 of the state's 19 Republican senators threatening to "put a nice little bullet" in their heads after they approved the measure, which bans collective bargaining by most public employees on anything other than base wages.

In the e-mails, Windels also claimed that several bombs had been placed in the lawmakers' cars, homes and inside the state capitol.

"Please put your things in order because you will be killed and your families will also be killed due to your actions," one e-mail read, according to the complaint.

When Windels was confronted by state investigators and asked if she had sent the e-mails, she said, "I think I said that but I don't know why I said that," according to the complaint.

Asked if she intended to follow through on the threats, Windels reportedly said, "No," according to the complaint.

Madison, the state capital of Wisconsin, is located in Dane County, where the complaint was filed.

(Reporting by James B. Kelleher; Editing by Greg McCune)

[Image via Auntie G, Creative Commons licensed]