Police said Thursday they found a chilling "to do" list scrawled on the arm of a 15-year-old girl arrested in the stabbing deaths of her grandparents: kill, keys, money, jewelry.

Holly Harvey (search) allegedly recruited her 16-year-old lesbian lover to help kill Carl and Sarah Collier in their suburban Atlanta home Monday, said Lt. Col. Bruce Jordan of the Fayette County Sheriff's Department.

He said the elderly couple, with whom Harvey lived, had ordered her to stop seeing the girl, Sandy Ketchum (search), and to stop using drugs.

"I believe the evidence at trial will be that the motive was to gain freedom and be able to stay together forever," he said.

When the girls were arrested Tuesday at a beach house on the Georgia coast, police found the to-do list written in ink on Harvey's arm along with three bloody knives and the girls' bloodstained clothes.

Police said the girls had jewelry in a bag, but do not believe there was cash in the couple's home. The girls fled in the grandparents' truck.

The girls are being held at separate youth detention centers. They made their first court appearances Thursday. The two will be tried as adults on charges including murder and armed robbery.

Police described Harvey as "stone cold" and a "manipulator" who allegedly persuaded Ketchum to sneak into the Colliers' home Sunday and hide under a bed with a knife until the grandparents, both in their 70s, were lured into the bedroom and attacked.

Both were stabbed more than 15 times.

The girls allegedly smoked marijuana just before the slayings. Jordan said they also had attempted to get guns by calling friends they had met during their times in juvenile detention centers.

Investigators said they had found a poem Harvey had written in which she described how depressed she had been and that she cried herself to sleep. The poem contained the line, "All I want to do is kill."

"She wished for everyone to suffer the way she suffered," Jordan said.

When the girls were arrested at the home of two boys they'd met on Tybee Island (search), Harvey laughed at the more than 25 arresting officers.

"She was callous and cocky. She is the coldest and most heartless individual I've ever interviewed. It almost made her giddy to know we had brought that many people to arrest her," Jordan said.

He said Harvey has not cooperated with investigators but Ketchum has. Jordan said the older girl strictly "was in it for the love."

On Thursday, the girls were escorted into court together, wearing bulletproof vests with their hands cuffed in front of them. Both sniffled as the charges were read.

Harvey's world "has been turned upside down. She still appears to be in shock," said Judy Chidester, her court-appointed lawyer. "She's acting like a scared 15-year-old, which is exactly what she is."