INDIANAPOLIS — The beast stands about 5 feet tall with brown eyes and blonde hair. And she likes to smile. A lot.

But don’t be fooled.

Mary Beth Dunnichay is lethal, a fact in stark evidence Saturday at the 37th annual IHSAA girls swimming and diving state finals.

The Elwood senior set a state record with 544.05 points and won a state diving championship by 106 points to complete her lone high school season.

“In my opinion, she stepped out to do this,” USA Diving National Training Center director John Wingfield said. “She was an Olympian already. What happens if she comes out here and doesn’t win? That was one of the questions we asked when she was planning this. But she said she wanted to do this for her school, for her community and to prepare for college diving. And she did a great job.”

Wingfield coached the 2008 U.S. Olympic team for which Dunnichay competed and has mentored her for much of her career.

But he was at the state finals merely as support.

The credit for this performance goes directly to Dunnichay and her Elwood coaches.

And it wouldn’t have been possible without the unique toughness of the diver herself.

Dunnichay teamed with Ohio State’s Katherine Bell last Sunday to win her third national championship on the 10-meter synchronized platform. Six days later, her surgically-repaired right shoulder still was sore enough to require repeated taping throughout the championship meet.

But Dunnichay never complained, and she responded with the best performance in state finals history.

“She’s such a strong-willed person,” Panthers coach Tammy Harris said. “Her shoulder has hurt her since last week. The girl amazes me. That’s all I can say.”

Dunnichay blitzed through the morning prelims and early afternoon semifinals with 379.85 points to take a 71-point lead into the final round. Madison County’s only other representative, Pendleton Heights junior Hannah Cochran, missed the finals cut by 2.25 points and finished 17th overall.

Dunnichay, who has specialized on the 10-meter platform for much of the past five years, began working again on the springboard just last May. She finished 17th in the 1-meter competition at last year’s U.S. Junior National Championships and 15th in the 3-meter competition, while claiming a national title on the platform.

As recently as Tuesday’s IHSAA regional, Dunnichay admitted she still wasn’t completely comfortable on the 1-meter board. In Indianapolis, those concerns were invisible.

“The transition’s hard, but her skills are great,” Wingfield said. “Whether it’s platform or springboard, diving at some level is simply diving. She has a great attitude, she’s a great competitor and she has a great head for the sport.”

She opened the finals with dive 401B, an inward pike, and scored 40.50 from the seven-judge panel. She received one 10 and one 8, but the two highest and two lowest scores are thrown out. A diver’s final award is determined by adding the three middle scores and multiplying by the degree of difficulty, in this case 1.5.

While Dunnichay’s score was the second-highest of the round, her overall lead actually decreased to 68 points. Any doubt about the final outcome, however, was erased on her next dive.

Dunnichay threw a 105C, a forward 2.5 somersault tuck with a 2.4 degree of difficulty. When she hit the water, one official sitting beside the diving well said simply, “It’s over, now.”

When the scoreboard flashed a 61.2-point award, Dunnichay’s win was secured. That gave her a total of 481.55 points through 10 dives.

Danville Community’s Lacey Houser finished second with an 11-dive total of 438.15.

Being assured of victory still didn’t stop Dunnichay from bringing the house down on her final dive.

She threw a 52233B, a backward dive with 1.5 somersaults and 1.5 twists and a ridiculous 2.5 degree of difficulty. When she nailed the dive, the 2,000-plus crowd erupted with its loudest cheers of the competition. When the scores were shown, the cheers grew even louder.

Dunnichay was awarded 62.5 points, bringing her total to 544.05 and eclipsing fellow Olympian Kelci Bryant’s state record by 40 points.

As she exited the diving well, Dunnichay stole a glance back at her scores and flashed a brief smile.

“It felt good, especially when I saw the final scores,” she said. “(Breaking the state record is) a big accomplishment.”

Dunnichay said the large crowd fueled her, and Wingfield said it might be the largest she’ll dive in front of before competing at the 2012 Olympics next summer in London.

After accepting her gold medal on the top of the podium, Dunnichay said she felt a mixture of excitement and relief.

“I’m excited because I actually met my goal,” she said. “But I’m also relieved that it’s done and I don’t have to worry anymore. And I’m excited about what my future holds at Purdue and everything else.”

Harris beamed like a proud parent and posed for pictures with Dunnichay after the diver finished a gauntlet of video interviews.

She said she was proud of the way Dunnichay represented herself and Elwood.

“She’s worked very hard for this,” Harris said. “And she accomplished all of her goals.”