Sex offender uses Walmart self-checkout scam to buy a crossbow - as cops hunt pervert on bizarre charge

• READ MORE: Dramatic moment mother confronts sex offender in Target 

Police in Philadelphia are searching for a registered sex offender after he managed to scam Walmart out of a crossbow. 

Investigators in Cumberland County are searching for Shawn Whiddon, 51, after he made off with the weapon in Lower Allen Township on Tuesday. 

Police say that Whiddon managed to scan a barcode that registered as a children's crossbow valued at $25, but walked out with an adult one worth $239.

Officers also suspect that Whiddon committed a similar theft at another nearby store and are seeking him for unlawful use of a computer and retail theft. 

Whiddon was placed on the sex offender register following a conviction in 2001 for the offense of attempted 'carnal knowledge'. 

The incident happened in Bedford County, Virginia, and he was originally indicted on charges of 'taking indecent liberties with a child'. 

Any further specifics on the case remain unclear at this time. He was ordered to have no contact with his victim and sentenced to three years in jail.  

In November 2007 Whiddon was also arrested after robbing a bank in Augusta, Georgia, of just over $4,100.

In court papers seen by DailyMail.com, he entered the Regions Bank and told the teller: 'I need all your hundreds, fifties, and twenties'. 

The teller said she initially thought Whiddon was joking as he smiling, before he added: 'This is no joke. No die packs or bait money. Don't make me come back there or hurt anyone. I'm desperate'.  

Officers found his abandoned car in the area after the incident with handwritten notes requesting money from the bank, but he failed to use them in the robbery. 

After police caught up with him later that same day inside a motel he gave a full confession. 

Whiddon later told a sentencing judge in 2008 that he had suffered with a drug problem for years and had robbed the bank to pay back drug dealers he owed. 

For the robbery he was sentenced to six and a half years behind bars, followed by three years of supervised release. 

In a court transcript, Whiddon previously told a judge that he was divorced and had two children of his own. 

He also said his occupation had been as an accountant for a plastics store in New York City.