The two had consumed a large amount of whiskey and beer after they completed another week in auto mechanics' school. Sitting on the banks of the Sacramento River on April 10, 2008, one of them suggested they take a stroll out onto the catwalk jutting off of the I Street Bridge.

In the darkness, Richard David Froemke and Robert Alexander Rodriguez meandered beyond a "no access" sign and onto what amounted to an unguarded 18-inch-wide plank that extends from the bridge over the river.

Only Froemke came back. Rodriguez fell into the river and drowned. Prosecutors eventually charged Froemke with involuntary manslaughter for allegedly leading the two on the catwalk trespass.

On Thursday, a Sacramento Superior Court jury – after just a few hours of deliberations – sided with the defense argument that if anybody was responsible for Rodriguez's death last year, it was Rodriguez.

The acquittal left the defendant speechless.

"I really don't know what to say," Froemke, 22, said in a brief interview on his way out of the courthouse with family and friends. "I'm sorry for their loss," he said, in a message to Rodriguez's family.

The jury's verdict similarly stunned Margarita Rodriguez, the mother of the 20-year-old whose body was recovered about 150 yards away from the bridge and a week after he fell off the catwalk – without Froemke reporting the incident to police.

"I'm not happy with it," she said, as she walked down the hall from the courtroom with Deputy District Attorney Eric Kindall, who declined to comment. "I think he should have at least been punished for not calling after being responsible that another human life's dead."

Both Froemke and Rodriguez were students at the WyoTech automotive repair and auto body school in West Sacramento. Both came from out of town, with Froemke hailing from Oregon while Rodriguez had family in Southern California.

"They were just typical 20-, 21-year-olds," said Froemke's lawyer, Assistant Public Defender Andy Read. "Both were becoming mechanics. They were both friends. It's a tragic incident."

The day they went out on the catwalk, Froemke said they persuaded somebody at Wal-Mart in West Sacramento to buy them a fifth of whiskey and two six-packs of beer, and that they got "completely smashed."

A coroner's autopsy later showed Rodriguez had a blood-alcohol level of 0.321, four times the legal limit to drive. Officials said the the figure was unreliable, inflated by the decomposed state of his body.

Kindall, in his rebuttal argument Thursday, told the jury it was Froemke who came up with the idea to go out on the catwalk, who instigated his friend to join him, and who aided and abetted the trespass onto the catwalk that posed a high risk of death.

"It was his idea," Kindall told the jury, in reference to Froemke. "He led the way."

Kindall said inconsistencies in Froemke's statements to police about what he did after Rodriguez fell into the water suggested a consciousness of guilt. In one interview, Froemke said he screamed for Rodriguez and was "scared to death."

In another he said "at first I didn't think it was too serious" and didn't call anybody because he thought his friend would be able to swim to the river bank.

"This was not just an accident," Kindall said. "This was not just a tragedy. This was a crime."

Read did not want to comment Thursday on the prosecution's case. The defense lawyer said "it was a just verdict" and that "ultimately the jury agreed that it was something Mr. Rodriguez equally chose to do, to go out there" on the catwalk.

Call The Bee's Andy Furillo, (916) 321-1141.