A medical examiner ruled Theresa Lockhart's death a homicide on Wednesday, Nov. 29.

The 44-year-old Portage woman went missing back in May, her body was finally found in a shallow grave in the Allegan State Game Area on Oct. 24, 2017.

Her body was found shortly after her husband, Christopher Lockhart, a primary suspect in her disappearance, was found dead inside their home. He left behind a confession letter admitting to choking his wife to death, along with a map to where her body was buried.

A specific cause of death could not be determined based on the decomposition of Lockhart's body. But based on the circumstances including the note left by her husband -- investigators ruled Theresa's death a homicide.

Read more: Christopher Lockhart, husband of missing woman Theresa Lockhart, found dead

According to his note, Christopher killed his wife on May 18, several days before she was first reported missing.

Theresa Lockhart was a Spanish teacher and a beloved sister, daughter and friend.

Previous coverage:

Portage woman with family in Grand Rapids area reported missing

Police search home of missing Portage teacher

'They were going through a rough patch,' friend of missing Portage woman speaks

Husband of missing Portage woman arrested for destruction of property

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