The arrest of bigwigs like former union minister A Raja, DMK MP Kanimozhi, sports czar Suresh Kalmadi, mining barons Reddy brothers in high-profile corruption cases kept the CBI in headlines during the year as it battled to keep its current organisational structure in the light of proposed Lokpal.

The agency which has a poor record in probing corruption cases against politicians managed to get an iron curtain around it from public scrutiny, as after its persuasion, the government agreed to exempt its functions from the ambit of Right to Information Act even though nodal department DOPT has termed the demand of CBI as "vague".

The CBI, which is facing shortage of over 1,000 officers, put its foot down before the government opposing any move to bring changes in its structure in the light of proposed Lokpal as the civil society and Team Anna demanded that the agency should be brought under anti-corruption ombudsman.

As the debate over the Lokpal touched a new pitch, demands to bifurcate the agency's corruption investigation wing were also raised which were strongly opposed by the CBI Director before the Parliamentary Standing Committee who demanded more autonomy and freedom in his police functions.

In the final Lokpal bill approved by the Cabinet, CBI has managed to retain organisational form as well as changes have been made in the appointment procedure of agency's Chief as it has been proposed to include Chief Justice of India in the process along with the Prime Minister and the Leader of Opposition.

While CBI battled to get exemption from RTI Act and retain its structure, the agency started concluding various aspects of country's most staggering corruption cases which include CWG scam, 2G spectrum scam, Adarsh land scam among others by filing charge sheets.

The CBI has so far filed three charge sheets in multi- crore telecom spectrum scam accusing politico-corporate nexus of indulging in country's largest scam in terms of over Rs 30,000 crore loss caused to exchequer in the award of licences to telecom companies.

The agency arrested and filed charge sheets against Raja, Kanimozhi, former telecom secretary Siddarth Behura and Raja's former private secretary R K Chandolia in the spectrum allocation scam.

Those who faced the CBI action also included corporates like Kalaignar TV MD Sharad Kumar, Anil Dhirubhai Ambani group Hari Nair, Surendra Pipara and Gautam Doshi, Unitech Wireless former MD Sanjay Chandra, Swan Telecom's Director Vinod Goenka, DB Group promoter Shahid Balwa besides his brother Asif Balwa, Rajiv Agarwal.

Later CBI also issued charge sheets to five other accused -- the then Essar group promoters Anshuman and Ravi Ruia, Essar group director (strategy and planning) Vikas Saraf, Loop Telecom promoters Kiran Khaitan and her husband I P Khaitan.

Companies like Essar group, Loop Telecom, Reliance Telecom Limited, Unitech Wireless and Swan Telecom have also been named in the spectrum allocation scam.

The agency is awaiting response to its judicial requests seeking information about some companies allegedly involved in the scam from various countries and would take a call on filing another charge sheet in the case.

Even as three charge sheets were filed by the agency, CBI expanded scope of its probe to all the telecom licenses awarded during 2001-07 and registered two fresh cases pertaining to takeover of Aircel by Malaysian giant Maxis during the tenure of Dayanidhi Maran and licenses given during the tenure of late Pramod Mahajan as telecom minister.

Apart from the investigations in Telecom Spectrum allocation, the CBI lagged behind in the probe in another major scam -- the Commonwealth Games scam -- as it could file just one charge sheet even though 15 cases were registered by it.

Failure to file timely charge sheet in the Queen Baton Relay case related to CWG scam came as an embarrassment to the agency as the court granted bail as key accused including CWG-OC additional Director General KUK Reddy among others were granted bail by the court.

Alleged swindling of funds on the National Rural Health Mission in Uttar Pradesh led to three sensational murders of health department officials in the state capital including that of additional CMO Y K Sachan who was found dead under mysterious circumstances inside a district prison.

The cases were handed over to the CBI which filed cases in the murders and siphoning off funds in the NRHM scam in the state.

While alleged irregularities of central funds were being reported from Uttar Pradesh, large scale illegal mining and exploitation of iron ore mines was alleged in Karnataka.

The agency arrested mining barons and former Karnataka minister Janardhana Reddy and his brother and brother-in-law, Karunakaran Reddy and Srinivasa Reddy in connection with alleged illegal mining case.

The CBI also handled sensational and complex cases of murder and kidnapping including the killing of RTI activist Shehla Masood in Bhopal, Bhanwari Devi disappearance case in Rajasthan, Ishrat Jahan fake encounter case among others.

The agency also made unsuccessful attempts to bring back fugitives from abroad, like former Jharkhand chief minister Madhu Koda's close aide Sanjay Chaowdhary from Dubai, Purulia Arms drop case accused Kim Davey from Denmark and Naval War Room Leak case accused Ravi Shankaran from England.

CBI faced strong criticism from various quarters on closure reports filed in politically sensitive Bofors scam and Aarushi murder case.

The agency had moved a closure report in Bofors case agency seeking to drop all charges against Italian businessman Ottavio Quattrocchi which was accepted by the court.

Courts also took cognisance of CBI's closure reports in some crucial cases like Aarushi murder, Soltam guns upgrade case which involved aide for former defence minister George Fernandes and Jagdish Tytler in 1984 anti-Sikh riots.

According to government data, the CBI filed 517 cases between January and October.