Lucknow, April 10: Police today arrested Atul Singh, the brother of a BJP MLA, in connection with the gangrape of an 18-year-old woman in Unnao in Uttar Pradesh and the custodial death of the victim's father, and a special investigation team (SIT) was formed to probe the matters.

"The SIT will go into the entire gamut of issues involved in the incident," ADG (Law and Order) Anand Kumar told a press conference here, after the MLA's brother was arrested in Unnao.

The woman has alleged that she was raped by BJP MLA Kuldeep Singh Sengar and his brothers, and blamed the lawmaker for her father's death.

The BJP MLA has rejected the charges as a conspiracy by his opponents. The police officer said that so far clean chit had not been given to anyone in the matter.

Kumar said the SIT would be headed by the Additional Director General (ADG) of Police (Lucknow zone).

The Superintendent of Police (crime branch) will be a member of the SIT, which will look into various aspects of the case and accordingly take action against those found guilty, he said.

"The entire gamut of the complaint...will be factored in by the SIT and whatever legal actions can be taken, will be taken," Kumar said.

The victim's father died in custody in Unnao yesterday, prompting her to charge that he was killed inside the district jail at the behest of the lawmaker. To a question about the possibility of any role of influential persons close to the MLA in the case, the ADG said, "The SIT will establish all that...As you know the SHO of the police station and five other policemen have been suspended on grounds of dereliction of duty and mala fide considerations. The entire issue will be reconstructed and whoever is culpable and whosoever has tried to shield any person will be taken to task."

Kumar said that the death of the victim's father did not take place in police custody. "Whatever incident of beating up the deceased took place, it occurred in the village. The police in fact admitted him to the hospital immediately. But, whether there has been impartial and proper investigation, all these facts will be probed by the SIT, which will holistically probe the entire issue and the guilty will be booked," he said.

Asked whether a clean chit had been given to the BJP MLA, the ADG said, "Nobody has given any clean chit to anybody. The investigation by the SIT will establish the culpability of anyone and everyone who is involved in this episode and action will be taken accordingly. I can tell you that no guilty will be spared...The SIT will interrogate all the persons involved in this case including the MLA."

Chief medical officer of Unnao, S P Chaudhary, said, "The death may have been caused by shock and septicemia due to peritonitis (inflammation of the lining of the inner wall of the abdomen)."

To a question whether the deceased suffered from colon perforation as a result of torture, Kumar said, "How colon perforation happened and where it happened is a matter of judicial inquiry."

According to a police spokesperson here, a crime branch team arrested Atul Singh, the MLA's brother, on the directions of the state police chief.

Earlier, four persons -- Sonu, Baua, Vinit and Shailu -- named in the FIR registered on April 4 for beating up the woman's father had been arrested. The complaint was lodged by the woman's mother. The woman's father was arrested on April 5 under the Arms Act after he was allegedly beaten up by the MLA's brother. Makhi police station SHO Ashok Kumar Singh and five other cops been suspended so far.