Police arrested a couple Monday in Sayama, Saitama Prefecture, on suspicion of starving to death their 3-month-old son in 1997.

Ai Yokoyama, 27, and her husband, Keiichi, 36, a company employee, were arrested on suspicion of withholding milk from their first son, Sena, resulting in his death from malnutrition.

Although an autopsy showed Sena had also sustained bruises and bone fractures, police originally said there was no evidence a crime had been committed.

However, they reopened the case following Yokoyama's arrest in January on suspicion of injuring her third son, who was 4 months old then, by pouring boiling water on his face.

Prosecutors released her in February, citing a lack of evidence that she willfully injured her third son.

Police have also been investigating the death of the couple's second son, who died in April 1999 at the age of 3 months after choking on milk.

Yokoyama claimed Sena was weak since birth and would vomit milk often, according to the police.

The third son has tentatively been placed in the protective custody of the Tokorozawa child counseling center in the prefecture.

The center has filed a request for official custody with the Saitama Family Court, while the parents are demanding their son back.