TUCSON, Ariz. >> Federal authorities are investigating the bogus lawsuit filed in the name of the man who shot former U.S. Rep. Gabrielle Giffords and 18 others in Tucson five years ago.

The U.S. Marshals Service is looking into whether a crime occurred when someone pretending to be Jared Lee Loughner filed the lawsuit by mailing it last week to a federal courthouse in Phoenix from Philadelphia.

It’s unclear whether authorities have a suspect in mind, but U.S. Marshal David Gonzales of Phoenix said he wasn’t aware of a connection between the case and a similar one in which someone pretending to be an Uber driver charged with killing six in Michigan filed a lawsuit against Uber.

Meanwhile, a federal court judge in Arizona officially dismissed the Loughner case after it became clear that it was fraudulently filed, said Brian Karth, the U.S. District Court-District of Arizona’s clerk.

The fake lawsuit resembles one that was filed in the name of Jason Dalton, an Uber driver charged with killing six people in a shooting rampage in Michigan last month. Both lawsuits were postmarked in Philadelphia and were filed within days of each other. Dalton is being held in Michigan; Loughner is in Minnesota.

Loughner fatally shot six people and wounded 13 at a political event in Tucson on Jan. 8, 2011. Giffords, the target of the attack, was seriously injured. Her spokesman said she is not commenting on the bogus lawsuit.

The convicted killer’s attorneys notified the court that he didn’t file or authorize the case, said Cosme Lopez, spokesman for the U.S. Attorney’s Office in Arizona.

“It’s our understanding that the lawsuit was not filed or authorized by Mr. Loughner. Earlier (Thursday), Mr. Loughner’s counsel wrote a letter to the Court confirming this understanding. Instead, it appears that a third party may have misappropriated Mr. Loughner’s identity for purposes of filing the lawsuit. Federal criminal law prohibits such conduct,” Lopez said in an email.

The Associated Press could not reach an attorney for Loughner.

Gonzales said it’s too early to know what charges the person who faked the lawsuits could face.

Federal lawsuits can be filed in person or by mail. Staff attorneys sort through new filings and send them to a judge, who either dismisses them or assigns them to another judge.

It’s common for inmates to file lawsuits, and the process to file a lawsuit is relatively easy, Karth said.

In Detroit, the U.S. Marshals Service is investigating whether a crime occurred when the handwritten lawsuit was filed in Dalton’s name, federal court spokesman Rod Hansen said. The hoax lawsuit named Uber as a defendant. Dalton was listed as the plaintiff.

Hansen said court employees don’t inspect lawsuits to determine what’s legitimate.

“Who are we going to appoint to decide if it’s real or not real?” he said. “By law, we have to accept it.”

A lawsuit is docketed in court even if a $400 filing fee is not immediately paid. But the case typically is dismissed if the filer doesn’t respond to a formal request for money, Hansen said.

“That’s usually when we’ll catch” a hoax or bogus case, he said.

In the Michigan case, authorities say that between picking up Uber fares, Dalton opened fire on people at three locations, and that he didn’t know any of the victims.

According to police, Dalton told investigators that “a devil figure” on Uber’s app was controlling him.

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