BALI, Indonesia » An Indonesian court found an American couple guilty of premeditated murder and sentenced them to prison on Tuesday in the killing of the woman’s mother on the resort island of Bali.

The Denpasar District Court sentenced Tommy Schaefer to 18 years in prison and Heather Mack to 10 years for intentionally killing Sheila von Wiese-Mack while vacationing last August. The badly battered body was found stuffed in a suitcase inside the trunk of a taxi at the St. Regis Bali Resort.

The three-judge panel said it decided to be lenient toward Mack, 19, because she recently gave birth.

“Her newborn baby badly needs a mother’s love and breastfeeding,” the verdict said.

The court ruled that Schaefer, 21, was guilty of battering von Wiese-Mack to death in a hotel room at the resort, and that his girlfriend Mack had helped with the Aug. 12 killing.

Schaefer and Mack, both from Chicago, were tried separately in the same court with the same judges and prosecutors.

They were arrested a day after the body of von Wiese-Mack, 62, was found in the suitcase in the taxi’s trunk.

They have a week to decide whether to appeal the verdict.

Von Wiese-Mack reportedly did not approve of the couple’s relationship.

The charge of premeditated murder carries a maximum penalty of death. Prosecutors had sought an 18-year jail term for Schaefer and a 15-year sentence for Mack.

Presiding Judge Made Suweda described Schaefer’s deeds as sadistic, but said his politeness and expression of remorse during the trial meant he did not receive a heavier sentence.

Schaefer testified at his trial that von Wiese-Mack was angry when she learned about her daughter’s pregnancy and tried to strangle him, prompting him to strike her with metal fruit bowl.

Prosecutors said Mack helped Schaefer stuff her mother’s body into the suitcase by sitting on it to enable Schaefer to close it. They then placed the suitcase in the trunk of the taxi and told the driver they were going to check out of the hotel and would return, but never did, prosecutors said.

They said Mack and Schaefer plotted to kill Mack’s mother because she didn’t endorse their relationship, and that Mack once proposed that Schaefer hire a hit man for $50,000.

Von Wiese-Mack was the widow of highly regarded jazz and classical composer James L. Mack, who died in 2006 at the age of 76.

One of Mack’s U.S.-based attorneys, Michael Elkin, said in a statement that he had asked how she felt, and she replied that she had prayed the following:

“Dear God, I know you don’t hear from me quite often, and I sometimes have acted like a jerk, but please have mercy on my soul and that of my daughter Stella, as I miss my mother and father so very much. Amen.”