Timothy Devey, 51, of Garden Street, pleaded guilty in Warrnambool Magistrates Court on Monday to one charge of possessing something likely to jeopardise the security or good order of the prison.

He was convicted and fined $1200.

The court heard Devey was in custody charged with murder when he attended the Warrnambool courthouse on January 21 for a committal mention hearing.

Prior to being transferred to the court, Devey was searched at the Warrnambool police station cells and found in possession of a two-centimetre razor blade.

The blade was attached to a piece of velcro in his right shoe.

Devey's lawyer said her client used the razor blade for "his artwork" at Port Phillip Prison.

"That is a primary outlet for himself and his mental health," she said.

"My client said the blade must have fallen into his shoe. He acknowledges it was there and accepts responsibility."

Magistrate Mark Stratmann questioned the man's story, asking how the blade could possibly have fallen into his shoe because it was stuck under velcro.

The lawyer said her client was adamant the razor blade did fall into his shoe and it was not a deliberate act.

She said that at the time of the offending, Devey was in custody charged with one count of murder.

She said that charge was recently downgraded to manslaughter, with Devey being arraigned and entering a guilty plea on October 8.

The charge relates to an incident on December 7, 2018, that left 45-year-old Warrnambool man Craig Blachford with fatal injuries.

Devey is expected to appear in the Supreme Court on December 3.

The lawyer urged the magistrate to discharge the matter relating to the razor blade.

She said Devey would likely receive a "very, very significant imprisonment term" following his plea in the Supreme Court.

She said he suffered a number of long-standing health conditions, including an alcohol-related brain injury, a "debilitating" nerve condition and depression.

The magistrate refused to discharge the matter, instead fining the man and recording a conviction.

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