APALACHICOLA, Fla. — A German woman showed no emotion Monday as a judge sentenced her to more than 21 years in prison after she pleaded no contest to drowning her 5-year-old grandson in the bathtub of a rented beach house.

The judge accepted a plea deal for Marianne Bordt, 73, over objections from the boy’s father, who wanted more prison time. Bordt, of Nufringen, Germany, had faced a potential death sentence for first-degree murder, but she was allowed to plead to a lesser second-degree charge for killing Camden Hiers in January 2010.

“I feel anguish and loathing for the person that is guilty of taking the life of my precious little boy,” said Camden’s father, David Hiers. “I want her to be punished as no person has ever been punished.”

Hiers of College Park an Atlanta suburb, wanted prosecutors to hold out for a 30-year term, but Circuit Judge Angela Dempsey imposed the agreed-upon sentence. Prosecutors also dropped an aggravated child abuse charge.

Bordt’s lawyers had been preparing an insanity defense claiming she did not understand her actions, in part because of injuries she suffered as a child from a Soviet bombing raid during World War II. The defense had lined up three experts who were going to testify she was legally insane against a single prosecution expert, who had waivered in his opinion, said State Attorney Willie Meggs.

An insanity verdict would have sent Bordt to a mental hospital and she then could have been freed if doctors decided she’d been cured, Meggs said.

“I did not want to gamble,” Meggs said. “This is a tragedy from the word go.”

Meggs said her age was a factor as well. Bordt would be 89 before she could be released under the plea agreement because state law requires felons to serve at least 85 percent of their sentences. The judge gave her credit for nearly three years of time served.