Mother decapitated by her son hours before her surprise birthday party, police say

A woman's decapitated body was found inside an Arizona home and her son was arrested in connection to the gruesome death, police said.

An investigation began on Friday, Sept. 27, just before midnight near Bethany Home Road and 43rd Avenue in Glendale, Arizona, when a family member called to report finding 49-year-old Teresa DeJesus Cruz Rubio dead.

"The family had prepared a surprise birthday celebration for the victim. Earlier that day at around 3:40 PM, family members contacted the victim, who had agreed to gather with them. When the victim failed to show up to the gathering, the family became concerned and went to her home where they discovered her decapitated body," police said.

Investigators had reason to believe the victim's son, Alejandro Gonzalez, was involved in his mother's death.

Gonzalez reportedly was using his mom's car around 5 p.m. that day. Not long after that, he reportedly used his mom's phone to call family members.

The car was found by Phoenix Police at 2:40 a.m. on Sept. 28 near 99th Avenue and I-10. Gonzalez was taken to the police station for questioning.

"Alejandro admitted to stabbing his mother numerous times using a kitchen knife, followed by decapitating her," police said.

He was booked into the Maricopa County Jail and is accused of first-degree murder.

A motive for the death wasn't detailed.