A man who was riding motorcycles with a friend killed in a crash with Rep. Bill Janklow (searchcried on the witness stand Tuesday as he described seeing his friend's mangled body lying in a soybean field.

"I kneeled down to see if he had a pulse and he didn't," Terry Johnson said as prosecutor Bill Ellingson showed him gruesome photos of the body.

Janklow, 64, is charged with second-degree manslaughter (search), speeding, running a stop sign and reckless driving for his role in the Aug. 16 collision that killed Randy Scott (search), 55, of Hardwick, Minn. Prosecutors say Janklow sped through the stop sign in a Cadillac and collided with Scott's Harley-Davidson.

The trial threatens to derail the career of a colossal figure in South Dakota politics. Janklow, a Republican, is a former state attorney general who served 16 years as governor during two stints before being elected to the state's only House seat last year.

Defense lawyer Ed Evans acknowledges that Janklow was speeding before the collision, but said he did not see the stop sign because he had a diabetic reaction that caused him to become disoriented.

Janklow frowned, took notes and looked forward as Johnson recounted the evening of the crash, telling jurors how he glanced back and noticed that Scott's "headlight wasn't there."

The emotional testimony came on a day in which prosecutors presented several graphic images from the crash, including a photo of Scott's body that showed most of his midsection missing.

The jury saw a video taken by the Highway Patrol just hours after the accident in which Janklow was told Scott's name and birth date. Janklow said something about Scott not even being 60 years old, then asked about his family, paused, sighed and said: "Jesus," as if it just sank in.

Jurors also looked at shots of the accident scene that show "Stop Ahead" and stop signs and a county road sign bent over by Janklow's car -- with the smashed-up Cadillac in the background. In addition, prosecutors presented close-ups of the car and the badly damaged motorcycle.

The videotape was taken when Trooper Jeff Lanning drove Janklow to the Flandreau hospital for a blood-alcohol test. During the ride, Janklow sounded coherent most of the time and was able to recall things, though he did not remember details of the accident. Toward the end of the tape it sounded like he was slurring his words.

Several times Janklow told the trooper he swerved and sped through the intersection to avoid hitting another vehicle.

"It was a white car," he said. "I thought that's who hit me."

But on the way back to the accident site, Janklow seemed to question whether he had seen the vehicle -- "Maybe I'm dreaming."

Prosecutors have said Janklow was going 71 mph in a 55 mph zone, but he denied exceeding the limit.

"I wasn't speeding," Janklow said on the tape. "I wasn't going fast."

Moody County Coroner Dr. Tad Jacobs said Scott died of extensive injuries to the torso and abdomen. He said it appeared Scott hit the trunk of Janklow's car, which was dislodged from the vehicle on impact.

Jacobs said Janklow seemed remorseful after the accident.

Prosecutors say Janklow knowingly barreled through the stop sign at the rural intersection as he drove home from a campaign event in Aberdeen. One witness testified Tuesday that Janklow's car passed her "as if I was standing still" just a few miles before she came upon the accident.

"It was very sudden. Zoom, and it was gone," said Monica Collins, who estimated her speed at 55 to 60 mph. "All I know is he was going a lot faster than I was going."

Three other people described what they saw when the car and motorcycle collided.

Brad Ilse said the accident happened less than a half mile in front of him, recalling a "body flying in the air."

Patty Jenkins broke down as she described seeing the accident. After the crash, she talked to Janklow's aide, Chris Braendlin, who helped Janklow out of the car.

"I asked if they were OK and he said yes," Jenkins said.

Her husband, Michael Jenkins, said the collision "was like an explosion of debris and dust."

Michael Jenkins said Janklow's aide asked him for candy for Janklow. Jenkins said he didn't have any but he asked a paramedic, who did, and gave some to Janklow.

Evans said during his opening statements that Janklow had a low blood sugar level at the time of the crash, which caused him to become disoriented.

If convicted of manslaughter, the maximum punishment is 10 years in prison. It would also prompt the House ethics committee to investigate.

The committee's rules say representatives who plead guilty or are convicted of a crime that carries two or more years in prison should refrain from voting or taking part in committee meetings in the chamber until his or her record is cleared or until re-elected.