The charge is in relation to the Feb. 12 murder of Christopher "Zeke" Burnett, 33, who was found dead in his house by authorities on Valentine's Day after his sister called and said she discovered his body.
Armstrong is being held at the Sunflower County Jail in Indianola on a $100,000 bond.
Armstrong's name had come up a few times in the ongoing investigation and Judge Gwendolyn Pernell ruled there was enough evidence to charge him.
Haywood said Armstrong knew Burnett prior to the murder but he was unsure of the extent of their relationship.
He allegedly ransacked Burnett's house, took jewelry and shot Burnett twice in the back of the head.
Haywood said there may be other suspects involved in the case and he has suspicion that the incident is drug related.
Armstrong may also face other charges related to theft.
"I won't feel good until we get to the bottom of all of this," said Haywood. "It will require tedious investigation to find out if more people are involved."
The murder happened at 170 Hunter Ave. in the New Edition subdivision outside of Drew city limits.
"We're still asking for the community's help so we can get all the details," said Haywood. "Anyone with information, please call the Sunflower County Sheriff's Department at 662-887-2121."
The case marks the second murder in the same neighborhood within the past six months.