WILLMAR — The attorney for a Willmar teenager charged in his grandmother’s killing asked a judge Friday to suppress part of his client’s statement to law enforcement.

Attorney Daniel Mohs argued that Bureau of Criminal Apprehension agents who questioned 18-year-old Robert Warwick did not advise him of his Miranda rights after telling him that he was under arrest and would face murder charges. Mohs asked that a portion of the statement not be allowed as evidence in Warwick’s murder trial.

Warwick’s grandmother, 79-year-old Lila Warwick, was slain during a robbery in her Willmar home on July 29.

Robert Warwick and 19-year-old Brok Junkermeier, also of Willmar, have been indicted on first-degree murder charges. Warwick allegedly masterminded the crime, suspecting his grandmother had more than $40,000 in a safe. Junkermeier allegedly stabbed and strangled her after making her write him a check. Both face prison sentences of life without parole if convicted.

Mohs also said he expects to ask for a change for venue for Warwick’s trial but will hold off for now, partly to see how much publicity Junkermeier’s trial will generate. Junkermeier’s trial is scheduled to begin in late March.

Lila Warwick was found dead in her home after authorities went to check on her. Someone called authorities after she failed to show up at a meeting at Redeemer Lutheran Church, where she was a volunteer.

Last week, a 16-year-old boy accused of acting as a lookout pleaded guilty to unintentional second-degree murder. Sentencing is set for Jan. 27.