Samm Henderson, 29, of Turner Drive, pleaded guilty in Warrnambool Magistrates Court last week to charges, including burglary, theft and going equipped to steal.

Magistrate Michael Coghlan said the 200 days Henderson had spent in custody on remand was enough and sentenced him to time already served.

On October 27 last year, Henderson and a co-accused rode their bikes to Warrnambool's Gateway Plaza about 3pm.

They entered the Kmart department store and stole five LEGO sets, one bicycle helmet and two skateboard worth more than $400.

The pair left the store with the items inside a shopping trolley. They then crossed the Princes Highway and attended the Our Lady Help of Christian's School.

Henderson and the co-accused placed the Lego and bike helmet, as well as their backpacks, in the doorway of a classroom before entering a music room through an unlocked window.

The pair began looking through cupboards and drawers but were soon scared by an alarm and fled the scene, leaving behind their belongings.

The assistant principal of the school was notified by a security company of the alarm and attended the property. He located the items and contacted police.

An inspection of one backpack uncovered the co-accused's driver's licence and personal cards.

The second backpack, which belonged to Henderson, contained an item hat was rolled up in cloth material and strapped with electrical tape.

The item was later inspected by a crime scene officer who removed the packaging, revealing a shot gun that had been altered by shortening the barrel.

Henderson's fingerprints were located inside the school.

He was also identified through CCTV footage.

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