Oru CBI Diary Kurippu

Oru CBI Diary Kurippu is a 1988 Malayalam mystery film directed by K. Madhu, written by S. N. Swamy, and starring Mammootty, Suresh Gopi, Jagathy Sreekumar, Mukesh, and Sukumaran.

This film is the first in the series of the CBI investigative thrillers featuring Mammootty as CBI officer Sethurama Iyer. It was produced by M. Mani under the banner Sunitha Productions. Sequels to the film are Jagratha (1989), Sethurama Iyer CBI (2004), and Nerariyan CBI (2005). A fifth sequel Veendum CBI in the franchise has been announced and is now in the pre-production stage.

The plot-line of the film, Oru CBI Diary Kurippu, was crafted around a real life incidence, the Polakkulam Case in which a hotel employee was murdered and dropped from the terrace to make it look like a suicide. The case was investigated by the CBI and it was in this case that a humanoid dummy experiment was first done in the state of Kerala to prove a murder case.

The lead character, Sethurama Iyer is said to have been inspired by a police officer named Radha Vinod Raju, Jammu and Kashmir cadre IPS Officer who in 2009 was appointed as the first chief of India's National Investigation Agency. He died in Kochi on 21 June 2012 at the age of 62, due to lung complications.

The movie was a huge box office success. The background score of the film became quite popular, and years after the release of the first two sequels, became popular as mobile phone ringtones. This was one of the reasons that led the filmmakers to plan a third sequel after 15 years. All the sequels use the same background score, composed by music director Shyam.

The film was remade in Telugu as Nyayam Kosam with Dr. Rajasekhar and in Hindi as Police Public with Raaj Kumar.
Mammootty's Sethurama Iyer was initially conceived as a Muslim character, but Mammootty suggested an Iyer character to incorporate jibes of Devadas (Sukumaran) about vegetarianism and lack of Iyers to do physical work. This resulted in one of the most popular two-character confrontation scenes between Sethurama Iyer (Mammootty) and Devadas (Sukumaran). Because of the popularity, this was repeated in the sequels Jagratha and Sethurama Iyer CBI. The third sequel was released 15 years after Jagratha. By this time, Sukumaran, who had portrayed Devadas, had died. Thus, Saikumar was cast as the son of Devadas; he was required to mimic Sukumaran's style of performance.
The movie was one of the first of its kind to concentrate on the central investigative story only, without the songs and dances generally associated with popular Indian commercial films.
CBI Diary Kurippu was one of the top grosser in 1988. It ran more than 200 days (175 days in TVM) in Kerala.