NORTH AUGUSTA - Krystina Shuttleworth's mother was supposed to be the one who put her cap and gown on for senior pictures.

These are the moments that make life so much harder, Krystina said.

She and her 12-year-old brother have coped well since their mother, Lisa Shuttleworth, vanished three years ago today.

But it's been a "really big struggle," Krystina said.

"The main thing that's getting to me at this point in my life is graduation is coming up, and she's not going to be there," the 17-year-old Midland Valley High senior said.

Ms. Shuttleworth's family has resigned themselves to the strong - and worst - possibility: That the single mother of two is dead.

What they want now, said Ms. Shuttleworth's mother, Lorraine Mabrey, is closure, to know what happened to her and for the person responsible to be charged.

Someone out there has the information that can make all that happen, Mrs. Mabrey said.

Police "are sure foul play was involved," Mrs. Mabrey said. "It's just that nobody's talking."

Investigator Charles Cain, who is now handling the case, said solving Ms. Shuttleworth's disappearance is still a priority for the Aiken County Sheriff's Office.

"We are still aggressively pursuing a very strong lead," he said. "It has not been put on the back burner at any time."

He declined to release many details about the status of the case - although Mrs. Mabrey hinted that she knows of a new lead authorities are pursuing - but said he has interviewed several people of interest in the past year.

"We have to wait for developments to arise," he said. "We have a good basic theory of where this is going to take us. Right now, it is still at the circumstantial phase."

Few details are known about what Ms. Shuttleworth did the last day she was seen, Sept. 4, 2003.

What is known is this:

About 7 that morning, she talked to Krystina, then 14, on the phone. Krystina had spent the night with a friend.

Ms. Shuttleworth took her son, Ryan, to Warrenville Elementary School, telling the then-9-year-old that she was going to see a friend that day.

About 8 a.m., an acquaintance spotted her at the Pit Stop convenience store on Pine Log Road. She must have stopped to get gas, her mother said.

She'd borrowed a white car from a friend, Neal Durden, who is now deceased. She called him at about 10 a.m., Mrs. Mabrey said, and also told him that she was expecting a guest.

All phone calls after 10 a.m. went unanswered, Mrs. Mabrey said.

Mr. Durden went by the house later that afternoon and found the Beech Island home locked tight. When Ryan got home from school, Mrs. Mabrey said, Mr. Durden brought the child to her house.

Mrs. Mabrey said that her daughter rarely missed meeting her son at the bus stop after school.

When Mrs. Mabrey, her husband and Ryan went back to the home with a key, they found both her daughter's car and the loaned white one in the driveway and a pot of tea on the stove.

Her purse was gone.

Someone took Ms. Shuttleworth, Mrs. Mabrey said.

"That's what we're thinking, that she left with someone and all signs say that she was planning to come back," Mrs. Mabrey said.

Ms. Shuttleworth, who would have turned 37 in June, would not have deliberately abandoned her children, Mrs. Mabrey said.

"She was an excellent mother."

Both Krystina and Ryan are now in the custody of their maternal grandparents.

Mrs. Mabrey is heartened by a new way a tipster can tell authorities what he or she knows, without fear of repercussion and with the hope of receiving a reward of up to $1,000. When her daughter disappeared three years ago, she said, Crimestoppers of the Midlands didn't operate in Aiken County.

Even if there are no eyewitnesses to what happened to her daughter, Mrs. Mabrey said she believes the person will eventually slip up and tell someone about being involved.

"If somebody has done something to her, how can they keep that inside?" she asked.

Bureau Chief Josh Gelinas contributed to this article.

Reach Sandi Martin at (803) 648-1395, ext. 111, or sandi.martin@augustachronicle.com