For the Grapevine Police Department, a promise made is a promise kept.
On Friday nearly a dozen officers surprised Sarah Medlin at her high school graduation in Mineral Wells.
Medlin is one of two daughters Officer Darren Medlin left behind when he was killed in the line of duty on June 12, 2004.
That night, his brothers in blue promised that they would be their for his family.
"Darren went out there and served this city and the state and paid the ultimate sacrifice," said Sergeant Bobby Smith, who joined the force the same year as Medlin. "We felt like we owe it as a friend and a coworker. We owe it to his family to basically be there for them for the rest of their lives."
Medlin was killed by a drunk driver during a routine traffic stop.
"We are never going to fill Darren's shoes. All we can do is try to be there as mentors and father figures to those girls," said Sergeant Jason Keller.
As graduates made their way onto the football field, Medlin was surprised to see the number of officers who showed up. She expected a few, but not nearly a dozen.
"I saw them from when I was walking in and I said, 'OK, those are my boys,'" Medlin said, choking back tears.
After receiving her diploma Medlin received a hug from every officer. Each one considers Sarah and her sister Laura to be their own daughter.
"She is very strong, determined.," said Keller. "The sky is the limit for her."
Medlin said making it this far wouldn't have been possible without the department.
"They'll always be there for me. I can't put into words how much I appreciate them," she said.