"I ... have great concern as to Mr. Martino's parenting skills, such as the overly excessive use of timeouts, sending our children to be(d) without dinner," she wrote.

Speaking Thursday from her home in Ukiah, in northeastern Oregon, Cunningham said she sent the letter because she was worried that Martino would hurt Zander, 3-year-old daughter Hailey and 1-year-old son Alan.

The children were in Martino's custody when Zander died.

"He was very rough with the kids," Cunningham said Thursday.

Still, she and her mother, Nancy Burr, 41, had not thought any of the children's lives were at risk.

"We were concerned about how he (Martino) disciplined the kids, but I never in a million years could believe he would do this. What would possess a man to take a hammer and beat your child to death?" Burr said.

That's what Las Vegas police allege the 25-year-old father did.

Martino and his live-in girlfriend, 22-year-old Brandi Reeves, have been in the county jail since Wednesday on charges of murder by child abuse.

Police allege Martino beat Zander to death on July 9 or 10. Hailey told a child protective services worker that "Dad hit Zander with a hammer" the night before paramedics were called to the home and found the boy dead, according to the arrest report.

Authorities charged Reeves with murder because, they allege, she didn't stop the abuse.

Martino and Reeves told police that they weren't responsible for Zander's death.

Martino gained full custody of the children in April.

A county official signed for the acceptance of Cunningham's certified letter on June 22, according to the receipt. Christine Skorupski, spokeswoman for the Department of Family Services, said the letter didn't contain anything indicating that the children were in immediate danger.

She wouldn't say what, if any, action was taken by county child welfare workers in response to the letter.

"Any kind of parental concerns brought to a case manager are addressed," she said.

On June 19, Zander and the other children were pulled out of their father's home when authorities discovered an injury to the boy. A family court hearing master returned Zander and his siblings to their father on June 28 because authorities couldn't determine that the injuries they had red-flagged were caused by abuse.

When Zander was an infant, child protective services determined that he had been abused.

In December 2004, when Martino and Cunningham were still together, Zander and Hailey were removed from the couple's care after the boy was found to have a broken femur, several broken ribs and a broken collarbone, Cunningham said.

She said in court in 2005 that she was responsible for Zander's injuries, but she said Thursday that she had falsely confessed because her attorney told her that confessing would get her children out of protective custody.

She said she never abused Zander or the other children.

After being born about a month premature and having to overcome breathing problems, "Zander was my angel child," Cunningham said.

She said that she believed Martino had hurt Zander in 2004 but that she had no evidence to support her claim.

A Family Court judge ordered Cunningham to stay away from the family in 2005, she said, so she moved to Oregon to live with her mother.

Since then, Cunningham has taken parenting, anger management and domestic violence classes in an effort to regain custody of her children, she said.

She has remarried and is living in a three-bedroom trailer next to her mother in a mobile home park.

She said she had been speaking to her children from Oregon about once a day. Zander's siblings are back in the custody of the county. Cunningham's mother hopes to win custody of them.

On Thursday, Cunningham asked authorities in Las Vegas to send Zander's body to Oregon instead of cremating him, as requested by Martino.