INDIO, Calif. -

A father allegedly beat his 10-week-old daughter to death, wrapped duct tape around her head and kept her body inside a trash bag that he and his girlfriend took with them from Desert Hot Springs to Arkansas, a prosecutor said today.

In a detailed, grisly opening statement, prosecutor Lisa DiMaria told jurors that first-degree murder defendant Jason Michael Hahn, 38, fatally struck his infant daughter Montana with a closed fist in February, 2001, inflicting severe skull fractures.

Montana's lifeless body was placed in a Tupperware container, which was then put in the trash bag and kept inside a trailer for a year at a storage unit in Arkansas, DiMaria said.

When Hahn and his co-defendant Krissy Lynn Werntz, 34, stopped making
payments, the trailer was auctioned off to an Arkansas man, who discovered the
bag in February 2002, DiMaria said. The man inadvertently placed the bag inside
a dumpster and saw what looked like a skeletal hand, prompting him to call police, the prosecutor told jurors.

Werntz is to be tried separately for Montana's murder.

Hahn was extradited to California from a prison cell in Vermont, where he had been convicted of killing his baby son Jason. That six-week-old baby was killed in 1999 and his body was found at an Arizona storage unit, DiMaria said.

Hahn pleaded no contest in 2006 to second-degree murder and was sentenced to 27 to 30 years in prison. Werntz was not charged in that case.

In addition to the latest murder charge, Hahn faces the special circumstance of having a previous murder conviction and one count of assault on a child causing great bodily injury. Hahn could face the death penalty if convicted of the special circumstances.

As if to prove her point, Hahn's third child -- also named Jason -- nearly died at the hands of his father after the first two were killed. But the second Jason, who was beaten at age four weeks, was the ``lucky one'' who survived a series of skull and rib fractures, DiMaria told jurors.

That boy was later adopted and renamed.

``He admitted to killing Jason and Montana'' when being questioned by
Arkansas police during the 2002 arrest for Montana's killing, the prosecutor said today.

But defense attorney Brenda Miller told jurors they should consider the bipolar disorder Hahn suffered since early childhood and that continued into adulthood.

Hahn endured other mental health problems such as anxiety, depression, agitation and even harbored thoughts of suicide ``all his life,'' Miller said in her opening defense arguments.

At 19, Hahn was placed in a group home for people with psychological
problems and was less-than-honorably discharged from the Navy, the defense
attorney said.

Miller likened Hahn's severe agitation to a swing that goes ``so high up, and goes so down low.'' Montana's cries made Hahn reach an extreme peak in his heavy mood swings, Miller said.

``Welcome to Jason Michael Hahn's world,'' Miller said.