Story highlights James Cartwright pleaded guilty to a charge of making false statements to federal investigators

Trump's remarks Friday evening fit a familiar pattern

Newtown, Pennsylvania (CNN) Donald Trump on Friday questioned whether a retired general who admitted in federal court this week that he lied to the FBI actually lied to the FBI, just the latest instance in which the Republican nominee has cast doubt on a key US institution.

"We just had a four-star general, highly respected, Gen. (James) Cartwright, heard what happened yesterday. Could go to jail for five years because he supposedly told a lie to the FBI. And I don't know that it was even a lie. I don't know," Trump said at his last of three campaign rallies on Friday.

Cartwright, a retired Marine Corps general, pleaded guilty on Monday to a charge of making false statements to federal investigators following an investigation into whether he leaked classified information to a reporter.

Trump has pounced on the case to argue there has been a double standard in the FBI and Department of Justice's prosecution of such cases, citing the Justice Department's decision over the summer not to file criminal charges in the case of Hillary Clinton's private email server.

But Trump on Friday took his criticism of the federal criminal justice system a step further by suggesting that Cartwright may not have actually lied to federal investigators.

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