Seanne Winters Barnette was found dead with an American flag draped over her body October 13 at her apartment on Baxter Lane.
John Winters, Jr. was found in Barnette's vehicle on the side of a highway by troopers in Virginia.
He was charged previously with stealing the car.
"The continual investigation revealed additional information that supported our initial beliefs and collectively lead to the first-degree murder charge," said Knightdale Police Chief Jason Godwin.
According to sources, the will of the sibling's father - a prominent Raleigh real estate developer and politician could have played a role in the murder.
Seanne Winters Barnette was named in that will, but her brother was left out.
John Winters Sr. died in 2004 and left all of his property to John Junior's other siblings and John Junior's son. Then, last year, the murder victim sued two of her sister's to remove them as trustees of the estate's trust fund.
Before it went to court the three siblings agreed to appoint a third party as trustee.