MANISTIQUE, Mich. (AP) — A jury Wednesday convicted a man of pushing his wife to her death from a 140-foot-high cliff at Pictured Rocks National Lakeshore.

Thomas David Richardson was found guilty of first-degree murder in Schoolcraft County Circuit Court. Many spectators wept and one person shouted, "Thank God," after the verdict was announced.

The jury, composed of seven women and five men, deliberated over two days at the conclusion of the six-week trial.

Richardson, 46, will be sentenced May 19. First-degree murder carries an automatic penalty of life in prison without possibility of parole under Michigan law.

His attorneys said they would appeal, describing Richardson as shocked over the verdict. Juanita Richardson's relatives said they were relieved.

The couple lived near the village of McBain in the northern Lower Peninsula, but were visiting the Upper Peninsula lakeshore when 43-year-old Juanita Richardson died June 22, 2006.

She is the only person known to have suffered a fatal fall at Pictured Rocks since it opened in 1972. Defense attorneys contended her death was an accident.

The trial was moved from Alger County, where the lakeshore is located, to neighboring Schoolcraft County.

Investigators said they were suspicious of Thomas Richardson from the beginning, as he gave conflicting accounts of what happened on the clifftop near the Miner's Castle overlook.

The delivery truck driver initially told police he didn't see his wife's fall but later said he did, first describing it as a suicide and later as an accident.

Friends and relatives who testified for the prosecution described the Richardsons' marriage as troubled and said Juanita had been planning a divorce. They said Thomas Richardson opposed divorce for religious reasons but had numerous affairs and abused his wife mentally and physically.

One witness, Kelli Brophy, acknowledged having had a close relationship with Thomas Richardson before his wife's death but denied they were sexually involved.

Brophy said Richardson told her he expected his wife to die of cancer and asked Brophy to wait for him. She said she told Richardson her ideal partner would be a churchgoer with no living ex-wives.

Brophy said Richardson called her on his cell phone the night before his wife died and visited her afterward, bringing a flower from Juanita Richardson's memorial service.

Investigators also found that the Richardsons had visited an estate attorney in Cadillac nine days before Juanita's death, and that Thomas Richardson wanted a will drawn up before their planned visit to Pictured Rocks.

Defense witnesses said Richardson was a dedicated Christian who loved his family.

"He was attentive to the needs of his children and his wife," said Paul Leifker, who lived with the Richardsons for a year.

Richardson didn't testify in his own behalf, but his three adult children said they believed he was innocent.