The circumstances that led two Rockville children--13-month-old Amani Renee Robinson and 2-year-old Andre Michael Whitworth--to be in the care of the same babysitter just before they died were similar, according to accounts given by both children's mothers.

In both cases, Timothy Conrad Phillips, 30, volunteered to sit with the children on the days they were later found unconscious, according to the mothers' accounts.

A source close to the current investigation said: "We think it's more than a coincidence."

Amani died Thursday at Shady Grove Adventist Hospital after a 911 dispatcher was told the little girl had drowned in the bathtub of her mother's Rockville home. Andre died on Feb. 2, 1997, two days after his mother found him unconscious and badly beaten in his crib.

Both children lived in the same neighborhood as Phillips at the time of their deaths, and their mothers said they had been befriended by him. Phillips has not been charged in either death. He surrendered to authorities Thursday on an unrelated theft charge and is being held at the Montgomery County Detention Center in lieu of $2,500 bond.

No attorney for Phillips, whose last address was in the 700 block of Lenmore Avenue, was listed in court records.

The Maryland state medical examiner has not yet determined the cause and manner of Amani's death, but Montgomery County police have described it as "suspicious." Andre's death was ruled a homicide and attributed to blunt-force trauma to his head, D.C. Medical Examiner Jonathan L. Arden said yesterday.

Lt. Michael L. Garvey, head of the Montgomery County Police Department's major crimes division, said investigators interviewed Phillips about Amani's death but have not interviewed him recently about Andre's. Garvey said Andre's death remains an open case--meaning that no one has been charged--because there was not enough probable cause to "indicate any particular person was responsible for the death."

Phillips and several other people who police said were at the Whitworth home at the time the boy was found unconscious were questioned soon after his death, authorities said.

Garvey said that at this time, "the only link that would be between the two cases was that there was an individual that had contact with the child prior to their death."

Through her mother, Beulah Whitworth, Andre's mother, Deborah Whitworth, relayed her account of the day she found Andre bruised and beaten .

In a telephone interview from West Virginia, where she now lives, she said that on Jan. 31, 1997, Phillips and Deborah Whitworth, then 20, were dating and that Phillips offered to watch Andre for the day.

Deborah Whitworth said it was not an unusual offer.

Whenever she needed to run errands, Phillips, who worked off and on, would take care of Andre. On that day, however, the child spent much of the day at Phillips's home directly across from Whitworth's in the Viers Mill Gardens Apartments in the 12500 block of Viers Mill Road, where he lived with the mother of his three children, Beulah Whitworth said.

Phillips, who always asked Deborah Whitworth to call him before she returned home, took Andre back to his home about 4 p.m., and put him in his crib, Beulah Whitworth said.

When Deborah Whitworth returned home, she was unable to wake her son. He was taken to Shady Grove Adventist Hospital and flown the same night to Children's Hospital, where he was pronounced dead at 11:49 p.m. two days later.

"He was in such bad shape, the hospital workers thought we needed to investigate it. His injuries were more than just a fall or an accident," Montgomery County police spokeswoman Ann Evans said shortly after the child's death.

Arden declined to say exactly what might have been used to strike Andre, but he said the blow's impact sent shock waves rippling through the 28-pound child's head, causing blood vessels to erupt, feeding a buildup of blood between the cranial cavity and the brain.

"It really is like tapping a block of gelatin with a spoon. You can see the jiggling. It's the destruction of forces, the shock wave running through the gelatin," said Arden, who explained that Andre sustained brain damage.

In an interview Monday, Amy Hogan, Amani's mother, said that she had left her daughter with Phillips at his suggestion. Hogan said that on the morning her daughter died, Phillips, who had spent the night at the family's Moore Street home, offered to care for her 4-year-old daughter and Amani for the day. Hogan said she bathed both her daughters and fully dressed them before leaving for work shortly after 8 a.m.

Montgomery County officials were summoned to the brick home about 8:40 a.m. after a caller told a 911 dispatcher that a child had drowned in the bathtub. When paramedics arrived four minutes later, they found Amani lying on her living room floor, and learned that no one had attempted cardiopulmonary resuscitation.

Authorities said neither the girl's hair nor the bathtub was wet.

She was taken to Shady Grove Adventist Hospital, where she was pronounced dead shortly after 9 a.m.

Authorities said yesterday that the only obvious injuries to Amani were to her genitals but said that additional tests will have to be conducted to determine the nature of the injuries. Authorities also said it may take a week to determine the cause and manner of Amani's death because of the lack of obvious external injuries.

Metro researcher Bobbye Pratt contributed to this report.

CAPTION: Amani Renee Robinson, 13 months, left, died Thursday while she was in the care of Timothy Conrad Phillips. In 1997, Andre Michael Whitworth, 2, died after having been in Phillips's care.