BOSTON -- The psychiatrist who prescribed medications for attention deficit hyperactivity disorder and bipolar disorder to a 2-year-old who later died of an overdose has agreed not to practice medicine, according to the Massachusetts Board of Registration in Medicine.

Rebecca Riley, 4, was found dead in her home on Dec. 13, 2006. Her death was ruled a homicide after an autopsy determined that she died of a lethal combination of several prescription drugs, including clonidine, a drug prescribed for ADHD.

Valproic acid, also known as Depakote; Dextromethorphan, a cough suppressant; and Chlorpheniramine, an antihistamine, were also found in the girl's system, the coroner said.

Riley's psychiatrist, Dr. Kayoko Kifuji of Tufts-New England Medical Center, diagnosed her with ADHD and bipolar disorder when she was 2 ½ and prescribed several medications for treatment, including clonidine for ADHD and Depakote and Seroquel to treat bipolar disorder.

Kifuji reached an agreement with the board to voluntarily halt her medical practice while the investigation into Riley's death is pending. All four members of the seven-member board who were present voted to accept the agreement.

"It requires and immediate cessation of practice. That absence for medical practice will stay in effect until such time as a final board action is taken," said Nancy Achin Audesse, a member of the Board of Registration.

"Dr. Kifuji is on paid leave from the hospital and has voluntarily agreed not to practice medicine during this time. Rebecca Riley's death is a terrible tragedy. We are bound by medical confidentiality and thus we can not expand further at this time," Tufts-New England Medical Center spokeswoman Brooke Tyson Hynes said in a statement.

Kifuji's attorney, J.W. Carney, quickly noted that the agreement is not an admission of wrongdoing.

"She absolutely did not over-prescribe, and her medical records will back that up 100 percent," he said.

Carney was asked if Kifiji advised Riley's parents that increasing the dosage of clonidine could be fatal.

"I am not going to go into any conversation that my client had with the defendant, but she has reported those conversations to the state police," Carney said.

The Board of Pharmacy has not opened an investigation.

"There is no basis at this time. It is a criminal matter," said Donna Rheume of the Department of Public Health.

"The dosage was appropriate, the drug was appropriate and the monitoring was appropriate," Carney said.

Riley's parents, Caroline Riley, 32, and Michael Riley, 34, pleaded not guilty to her murder on Tuesday and were ordered held without bail.