Vickie Gambrell was absolutely certain she'd put $20 on the counter when she went to buy gas at a mini-mart.

So sure, Delaware State Police say, she beat the clerk and threatened him with a scissors.

But, boy, was Gambrell wrong. She ended up under arrest after she returned to say she was sorry.

State Police spokesman Cpl. Jeff Whitmarsh provided this account of a transaction gone awry.

Shortly before 11 a.m. Thursday, the Claymont woman stopped at a Country Farms minimarket in Wilmington intending to buy $20 worth of gasoline.

But when the cashier told Gambrell she'd only given him a single dollar, the woman became livid.

Gambrell, 53, was adamant. She had given the clerk a 20. The clerk was just as sure Gambrell had only given him a buck.

They argued. She fumed. She stormed in and out of the store. She cursed and screamed. She accused the clerk of cheating her by committing a switcheroo.

Then Gambrell bounded behind the counter and punched and kicked the clerk. She reached for a pair of scissors and held its point against his throat, demanding $20 back, Whitmarsh said.

The clerk, fearing for his life, gave her two $10 bills. Gambrell left with the sawbucks.

The clerk called the police.

Before the troopers arrived, Gambrell sheepishly returned.

She approached the clerk. And put the two tens back on the counter.

She'd made a small mistake. As she drove away from the minimarket, she had peered into her purse. And there was the $20 bill. The very same bill she thought the clerk had pilfered from her.

Whitmarsh said it was a little too late for an "I'm sorry."

When troopers arrived, they arrested Gambrell and charged her with possession of a deadly weapon during the commission of a felony and several other counts.

Gambrell was released on $8,500 bond after being briefly held at the Troop 6 barracks.