The 34-year-old was arrested by Portland police detectives on Monday afternoon after cleaning out the woman's bank account during the past six months.

Detective Sergeant Jason von Tunk, of the Portland police crime investigation unit, said the man had befriended the elderly woman, stole her bank card and obtained her bank card PIN.

"We will be alleging he used the card on 38 occasions to steal in excess of $30,000," he said.

"He's drained her of all her savings. She's gone to the bank and been told she had no funds in her account.

"The man was already on bail charged with child porn offences."

The man was arrested, interviewed, charged and remanded in custody overnight Monday to appear in the Warrnambool Magistrates Court on Tuesday for a bail/remand hearing.

Earlier: Sergeant Daniel Lehmann said the offending was targeted and deliberate.

"This is very calculated behaviour," Sergeant Lehmann said.

"The money was taken from the account in a number of transactions, both in cash and by making purchases.

"The man has been charged with 39 offences including theft and charges relating to the bail act."

Sergeant Lehmann said the man's application for bail after being charged was refused by police, and he is now scheduled to appear in the Warrnambool Magistrates Court on Tuesday.

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