Federal prosecutors had recommended a 28-year sentence for Heather Mack for conspiring with her boyfriend to kill Sheila von Wiese-Mack in 2014.
The government also wanted Mack, 28, to get five years of supervised release, a $US250,000 ($A381,300) fine and restitution of $US262,708 ($A400,677).
In a filing last week, prosecutors said the recommended sentence "is warranted and sufficient, but not greater than necessary to serve a just and appropriate punishment for Mack's heinous crime".
The sentencing hearing began on Wednesday morning in Chicago with testimony from Bill Wiese, Wiese-Mack's brother and Mack's uncle. He asked Judge Matthew Kennelly to impose the maximum sentence possible, saying Mack has never shown remorse.
"If it were up to me, Heather would spend the rest of her life behind bars," Wiese said.
Mack, who wore an orange jumpsuit, orange slip-on shoes and glasses, remained mostly impassive as her uncle spoke, occasionally looking at attendees and giving small smiles to some.
Mack pleaded guilty in June 2023 to one count of conspiring to kill von Wiese-Mack with her then-boyfriend to gain access to a $US1.5 million ($A2.3 million) trust fund.
Prosecutors have said Mack, then 18 and pregnant, covered her mother's mouth while Tommy Schaefer bludgeoned Wiese-Mack with a fruit bowl in a hotel room.
Prosecutors said Mack and Schaefer had planned the killing for months, and that video evidence showed Mack and Schaefer trying to get the small suitcase containing Wiese-Mack's body into an Indonesian taxicab.
Mack, who lived with her mother in suburban Chicago's Oak Park, served seven years of her 10-year Indonesian sentence for her 2015 conviction of being an accessory to Wiese-Mack's murder. She was deported in 2021 and US agents arrested her on her arrival at Chicago's O'Hare International Airport.
Mack's daughter, then six, was with her when she was arrested. The girl was placed with a relative after a custody fight.
Mack's lawyers had sought a 15-year prison term, but with credit for her seven years in the Indonesian prison. She automatically was credited for the more than two years she spent in custody in Chicago.
The plea agreement called for a sentence of no more than 28 years and for two other charges to be dropped.
Schaefer was convicted of murder and he is serving an 18-year sentence in Indonesia. He is charged in the same US indictment. His mother, Kia Walker, was in the courtroom on Wednesday for Mack's sentencing.
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