SUPERIOR, Colo. -- Boulder County investigators arrested 34 year-old Stephanie Rochester on charges of first-degree murder and child abuse resulting in death.

Rochester was arrested about 5:55 p.m. Tuesday.

Workers from Avista Hospital notified the sheriff's office of the death of a 6-month-old baby boy.

The baby was identified as Rylan Rochester.

"Investigators were told the parents found the infant unresponsive in his crib," said Cmdr. Rick Brough, of the Boulder County Sheriff's Office.

An autopsy was performed Tuesday.

"The cause and manner of death are pending further laboratory tests and investigation," said Thomas Faure, Boulder County Coroner.

"The investigation revealed the death of the infant was intentional," said Brough.

Neighbors who spoke to 7NEWS off-camera are heartbroken. Everyone said the couple seemed so happy.

Two neighbors told the Daily Camera Rochester was suffering from postpartum depression.

Specific details on the case are not available as the case has been sealed.

Rochester is being held at the Boulder County Jail on a $750,000 bond.