Tasked with supervising foster child Rilya Wilson, former child welfare case worker Deborah Muskelly admitted Tuesday that she failed.

She charged taxpayers for gas mileage for visits to Rilya’s home that never happened. Burdened with a heavy caseload, Muskelly satisfied herself to not check on Rilya in person. The girl’s de facto caretaker, Geralyn Graham, always canceled in-person visits and vouched for the girl’s well-being, Muskelly said.

“She always painted a rosy picture,” Muskelly, 55, testified Tuesday in a Miami courtroom in which Graham is being tried for the murder of Rilya.

The 5-year-old disappeared more than a decade ago and has still never been found.

“Since the baby went missing, it’s been a nightmare,’’ Muskelly said. “I wish I had paid closer attention to all my children, not just her. I wasn’t looking at the tell-tale signs. I’m not proud of what I did. I am very sorry.”

Graham, 66, is charged with first-degree murder, kidnapping and aggravated child abuse. She was indicted in 2005 after allegedly confessing to a cellmate that she smothered the child.

The girl’s disappearance sparked massive upheaval and reform at the Florida Department of Children & Families in 2002, leading to a series of unbridled public hearings, a scathing report and legislative changes.

At least 11 DCF employees were fired or allowed to resign after the Rilya case generated intense scrutiny on the agency.

The agency’s role in the girl’s disappearance has taken a central role in the trial, now in its second week. The department did not notice Rilya was missing until April 2002, more than a year after she was last seen alive.

Graham told investigators that a mysterious DCF social worker whisked Rilya away for mental health treatment, a claim prosecutors say is bogus. To others, Graham gave conflicting accounts of what happened to the child — including telling one family friend who testified Tuesday that Graham claimed Rilya left to live with her biological mother.

As for Muskelly, her role in the girl’s tragic life has been highly publicized. After Rilya’s vanishing, she was arrested for falsifying time sheets showing she was working for DCF when she was actually substitute teaching at Miami-Dade schools.

She agreed to five years probation and had to pay back money prosecutors said she stole. Muskelly originally resigned from DCF because of an unrelated internal investigation into her conduct.

On the stand Tuesday, Muskelly said Rilya’s first foster home was a loving environment, despite occasionally unkempt conditions.

But Graham filed a complaint with DCF about the home’s shoddy conditions, which lead Muskelly’s supervisor — while Muskelly was on vacation — to remove Rilya and place her with Graham and her lover.

Muskelly testified Tuesday that she did not agree with the decision to remove the child from her original foster mom, Pamela Kendrick.

“I literally begged [my supervisor] to allow the kid to go back to Mrs. Kendrick’s house,” Muskelly said.

Willie Harris, her supervisor who was also fired, testified last week that he ordered Rilya removed from Kendrick’s home despite not having seen the living conditions for himself.

Rilya was placed in the Kendall home of Graham, who also cared for the girl’s baby sister.