By Rachelle Murcia
Coronado, CA (KGET/CNN) - The parents of two siblings shot and killed in California are opening up about their loss.
Navy Lieutenant David Reis and his sister, Karen, died on New Year's Day.
David and Karen Reis shared a close bond at a young age. They snuggled side-by-side in a childhood photo.
"When they were together, they would always get a picture together," said their father, Tom Reis.
Their last picture together would be their last night alive. The photo was snapped New Year's Eve, just a few hours before they were shot to death, along with two other men inside David's Coronado condo.
Originally sheriff's investigators said David's roommate killed the other three before killing himself, but now they won't say who pulled the trigger.
"It hasn't really all the way hit yet. It's still pretty unthinkable. Still kind of raw," said their mother, Patty Reis.
David was outside talking with a friend when he heard gunshots inside.
As he ran into his home, he was shot and killed in the doorway.
"He took protecting his sister very seriously. As much as I'd like to think he would have thought twice before entering the condo in San Diego, we know he didn't. He took his job seriously," said Tom.
On New Year's Day Patty was home watching television when she first saw the news that four people had been fatally shot in San Diego.
"I went to my computer. As I got more nervous, it just didn't feel right. I punched in a few things and about the third screen that came up, I saw his address. It was pretty much from that point on I knew they weren't alive anymore," she said.
"I still think sometimes they are going to walk through the front door. Or I'll start to text them or call them, but I'll realize I can't. But I definitely talk to them still," said their sister, Melanie Reis.
The Reis family spent their final Christmas together at David's Coronado condo.
"Every day was an adventure with them, trying all the things you would initially be hesitant to do. You wouldn't hesitate with David and Karen, you would just do it," said Melanie.
David and Karen lived for adventure. David had a passion for flying, even at a young age with his tiny cardboard cut-out wings, trying to take flight in his family's driveway.
Karen was right there by his side, making sure he attempted a safe take-off. When David died, he was an FA-18 jet pilot based at Miramar Air Station in San Diego.
In a home video, David shared his love for flying with his family. That love was just as strong as his love for his sister, a standout volleyball player and UC San Diego graduate.
"Hearing all the stories of what they did to help people, that was really humbling. David helped somebody through their college physics class after they flunked three times. He tutored them through. We got a couple of cards from people who went on to grad school at UC San Diego. They said they wouldn't have done it unless Karen would've have encouraged them," said Patty.
The Reis family wants others to share the unselfish spirit that David and Karen personified. They have created the Reis Ripple, bright bracelets that challenge people who wear them to help others feel special and succeed.
"If we would all choose to be more positive and live selflessly like they did, our lives will, the things that we do to touch other people will ripple out," said Patty.
The investigation into the killings continues.
Police are waiting on lab results from the crime scene.