DENVER -- The mother of the 4-month-old girl who died last month said the Denver Department of Human Services only made a cursory visit to her house to investigate accusations that her boyfriend repeatedly dropped the child.

But Mary, who asked that her last name not be used, said DDHS took her three other children away from her once Luz Valdez died.

"I didn't do anything to Luz," Mary said. "I should not have to be suffering like I am. I already lost one of my kids and I (am) feeling like I'm losing all my other three and it's making me go crazy. I did everything right."

Luz died Dec. 30, and police have charged Isidoro Valdez-Ruelas with first-degree murder and child abuse resulting in death. He was advised of the charges against him Wednesday.

Luz is the third child in less than 8 months who died after the family was under DDHS investigation of allegations of abuse. Chandler Grafner, 7, died in May after Human Services workers did not check out a school official's complaint that he had been missing for a month, and Niveah Gallegos, 3, died in September after failing to remove the girl after there was an allegation she was sexually abused.

Denver Mayor John Hickenlooper answered questions Wednesday afternoon about DDHS's handling of the three cases but said he is standing by his DDHS director Roxane White.

After she brought Luz to a doctor and told him that Valdez-Ruelas dropped her twice, a DDHS worker stopped by her Denver apartment, Mary said.

But the worker did not speak Spanish and didn't question Valdez-Ruelas about the incidents. The worker only checked out whether there was proper baby furniture, and through Mary, advised Valdez-Ruelas of the proper way to care for Luz.

"Social services came to my house, looked at her crib, looked at my son's room and the front room that had a high chair, a swing, a playpen, a little jungle gym," Mary said. "(Luz) could lay on the floor and play and so she said everything was OK ."

The DDHS worker told Mary she was closing the case, and directed her to a program where she could get help with acquiring food and furniture.

Mary and her brother, Mel, were surprised to learn that DDHS considered the case high risk but nevertheless dropped it after a month.

Mel said he believes DDHS dropped the ball and then took Mary's other children to make it look like they're protecting families.

"If she was so high risk, how come they left her in the home?" Mel asked.

Mary said days after Christmas, when she came home from work, the baby was repeatedly vomiting but she thought it was the flu. The next day Valdez-Ruelas kept calling her to tell her the baby was sick and when she came home Luz was near death.

"When I got home, he handed me the baby," Mary said. "She was limp, she wasn't breathing right. She was almost dead."

The baby was in life support at Children's Hospital and Mary had to make the agonizing decision to take her off life support Dec. 30.

"I removed her from life support but she was already dead," Mary said. "There was no chance of her living by herself."

The state started a death investigation into the case, which should be completed within 90 to 120 days, and Hickenlooper said he is meeting with consultants as soon as next week to determine if something should be done right away.