USDr. Dan Sickles pulled out a pistol and shot his wife's mistress right near the White House in 1859.

Sickles shouted: "You're a scoundrel, you make my family dirty, you must die!".

Dan Sickles was born into a wealthy family in New York and studied law.

Both Dan and Teresa have an affair.

In the early spring of 1858, Teresa had an affair with Barton Key, a close friend of Sickles and the son of Francis Scott Key, the lyricist for the American national anthem.

To make a secret appointment, Key often signals to Teresa by standing on the road waving a handkerchief.

On February 24, 1859, Sickles received an anonymous letter accusing his wife of adultery.

Three days later, Sickles saw Key standing outside his house waving a handkerchief to Teresa.

Sickles fired the shotgun before Key could say a word.

Sickles killed Key in Lafayette Park on a sunny Sunday afternoon.

"The affair that ended with this tragedy caused a stir throughout the United States," the New York Herald wrote.

Even President James Buchanan expressed his views on the sensational case.

The Harper's Weekly predicts the results before the trial begins: "The American public will find it sensible that the lawmakers murder to humiliate themselves".

Dan Sickles hired eight lawyers to defend him in the trial.

"Temporary madness" was then a new concept in American courts.

But Graham relied on the jury's sympathy for Sickles.

"An adulterous woman will expect her husband to die, maybe with a cup of poison, a dagger or a pistol," another defense lawyer said.

The judge doesn't overly believe the "temporary crazy" plea.

However, the jury only took an hour to declare Dan Sickles not guilty of "temporary madness".

Although Sickles' case was the first to be acquitted on the grounds of "temporary madness", the jury almost certainly didn't believe that argument.

However, this ruling created a new legal basis for the US legal system.

After the case was closed, Sickles once again caused a stir because of reconciliation with his wife instead of divorce - a decision that caused him to be criticized by colleagues and the media.

The congressman sent a letter to the New York Herald on July 19, 1859, begging the public to leave Teresa alone and vent his anger on him.

"We hope those who sympathize with Sickles, especially the jury, have honored him as a great defender of the solemnity of marriage satisfied with this result," the Baltimore American satirized.