The beating occurred in the woman's El Cajon, California home last week.
Investigators said Shaima Alawadi was found in the dining room by her 17-year-old daughter at 11:15 a.m. Wednesday.
She had suffered severe head trauma.
Alawadi was transported to a local trauma center and died Saturday, March 24 after being on life support for three days.
Neighbors said the family, which includes as many as five children, moved into the rented home in El Cajon about two months ago.
Alawadi and her two daughters wore headscarves, according to their neighbors.
Police said a threatening note was discovered very close to where the victim was found.
The victim's family stated they had found a similar note earlier this month, however did not report it to authorities.
Police would not confirm the contents of the note, and when asked if the note suggested that it could be classified as a hate crime, said investigators are not eliminating any possibilities at this point.
A local chapter of the Counsel of American-Islamic Relations said they are distressed about the note sent to the family.
"We are obviously concerned about the possibility of a hate crime," said CAIR Executive Director Hanif Mohebi.
He said the family received a threatening note a few weeks back and then this happened.
"The body was found with a note that essentially says, 'You guys are terrorists, go back home, you don't belong here.' That's the message," Mohebi said.
Alawadi's report has been sealed by the medical examiner per a police request.