The accused was identified as Budumuri Anil Babu, a Home Guard constable attached to the city police.
According to Additional Deputy Commissioner of Police (Crime) S. Varada Raju, the complainant Karri Someswara Rao (72) had gone to consult a doctor at Doctor and Doctors Plaza on December 8, 2014.
After consulting the doctor he had gone to a medical store to purchase medicines and at the store he accidentally dropped his SBI ATM Card.
The accused who was present close by noticed it and picked up the card. Since the complainant was a 72-year-old man, he had written the PIN number on the backside of the cover of the ATM card for reference.
The accused used the number to withdraw Rs. 20,000 in four transactions, said Cyber Cell Inspector K. Satyanarayana Rao.
Basing on CC TV footage, the police zeroed down on the accused and arrested him on Monday.
The accused was booked under Section 66 C of IT Act.