"It's hard to see all the pictures. How happy she was. Her birthday is coming up, and we're going to want to call her, and she's not going to be there to call," said Cunningham.
Katherine Cunningham was killed earlier this year in February.
She was found beheaded close to a bunker filled with guns on Camano Island in Washington.
Her alleged killer, Jacob Gonzales, is facing new charges for the murder after island county investigators say DNA on the handle of a samurai sword found matched his DNA.
The blood found on the blade also matched Katherine's.
Gonzalez is still on the run, and authorities believe he could be hiding out in Merced County.
RELATED: Man accused of beheading woman with a samurai sword may be hiding in Merced County, authorities say
"We have the confirmation that he was the one who did it, but we still don't have him, so it's another waiting game," said Cunningham.
Los Banos investigators say they initially were notified by the island county sheriff's office.
They followed up on some leads, but none ended in an arrest.
However, the Merced County sheriff says the Washington agency never notified them.
HAVE YOU SEEN HIM? The Island Co. Sheriff's Office in Washington state is charging Jacob Gonzales with new domestic violence murder charges for allegedly beheading an Atwater woman earlier this year. He's on the run, but believed to be in the Merced County area. @ABC30 pic.twitter.com/4HEmPzFyr5— Nathalie Granda (@NathalieABC30) July 4, 2018
"I'm reading here nationwide warrant, yet it hasn't come to us officially, so it's frustrating to know there's a bad guy running around my county, and the investigating agency hasn't taken the time to contact us to see if we can help," said Merced County Sheriff Vern Warnke.
Cunningham says her sister was in the Air Force and loved to take care of the elderly.
She is left wondering why anyone would do this to Katherine.
"We just need answers and the closure knowing that he's not still out running around like its fine," said Cunningham.