ST. LOUIS (AP) — Alyshia Strong was effectively left an orphan 14 years ago when her father killed her mother and half-sister during a violent argument in a St. Louis County apartment. Still, the girl is urging Gov. Jay Nixon to spare his life.

Richard Strong, 48, is scheduled to be executed at 6 p.m. Tuesday.

Eva Washington and her 2-year-old daughter from a previous relationship, Zandrea Thomas, were found stabbed to death on Oct. 23, 2000, in her apartment in St. Ann. A large butcher knife was on a bed next to a pool of blood. Alyshia, then just 3 months old, also was on the bed but unharmed.

Alyshia, now 14, said in an interview with The Associated Press on Monday that she has forgiven her father. They visit frequently at the prison in Potosi. She said her father plays an important role in counseling her.

"He's always been with me," she said. "He's the only surviving parent I have, and I struggle in life. To see my father live would help me."

Scott Holste, a spokesman for Nixon, said the clemency petition is under review.

Strong's attorney, Jennifer Herndon, also has filed appeals to the U.S. Supreme Court — one on a procedural matter, the other claiming that Strong shouldn't be executed because he suffers from severe depression.

Strong is remorseful for the crime, Herndon said. She said that both he and Washington suffered from mental illness and frequently argued.

"It wasn't a healthy relationship," Herndon said. "He just snapped."

Alyshia Strong went to live with Strong's mother after the killings, a woman Alyshia now refers to as "Mama," the clemency petition said.

Alyshia said in the petition that she is asking the governor to spare her father because she thinks "it is wrong for me to have another loss. I understand that my father needs to face consequences and to pay for what he did, but I do not think it is right for me to lose my father as part of the punishment."

She recalled in the petition when she told Strong about a fight she was involved in. He was disappointed to learn of the fight and "also told me that he thought I could find other ways of dealing with my problems — ways that did not include fighting," Alyshia wrote.

"My father told me that I should stay clear of the drama at school, and stay focused on the books, not the people. I listened to my father's advice, and I can honestly say that I had less drama in my school year than I would have if I had not listened to my father."

The execution would be the fourth in Missouri this year. Only Texas, with eight, has had more. Missouri and Texas tied for the most executions in the U.S. last year with 10 each.