Members of the Santosh Jha gang allegedly threatened officials of a private construction company in Sitamarhi that had not paid up extortion money demanded by the gang, which is the same one believed to be behind the murders of two engineers in Darbhanga.

The company, RCD Infrastructure Private Limited, is constructing a bridge on the Lalbakia river between Phulwaria and Jamua ghat in Sitamarhi district, around 180km north of Patna.

A senior official of the company lodged a complaint with Barginia police station on Wednesday afternoon, prompting superintendent of police Hari Prasath S. to strengthen security arrangements at the firm's base camp. Hari Prasath said: "We reviewed the security arrangements at the base camp in wake of the recent development."

In Darbhanga, cattle trader Mohammad Arif (60) was bludgeoned to death. Arif had gone missing on Wednesday from his native village, Gaura, under the jurisdiction of Kuseshwarsthan police station. Early on Thursday morning, his body was found in the barren field on the outskirts of the village, a police officer posted in Darbhanga said.

In Patna City, trader Saurabh Jaiswal was robbed of Rs 1.27 lakh by gun-toting criminals near Chailitand under the jurisdiction of Alamganj police station. The police picked up the trader's domestic help, Golu, for interrogation.

In Kishanganj, the 16-year-old son of a businessman was kidnapped allegedly for ransom on Wednesday evening. Ram Sogarath Rai, a hardware dealer of Kishanganj and father of the kidnapped boy, received a ransom call on his cellphone on Thursday morning. The anonymous caller told Rai that his son, Siddhant, was in their custody and would be released only after payment of Rs 20 lakh.

Rai was sitting in the Kishanganj police station to lodge a missing complaint when the alleged kidnapper demanded ransom. Siddhant, an undergraduate student of a local college, went missing on Wednesday evening.

The victim's father told the police that Siddhant had left home saying that he would return within half-an-hour. He was last seen with his friends near Paschim Pali Chowk in the heart of Kishanganj town, around 360km northeast of Patna. The family apprehended foul play when he did not return home. "Initially, we searched Siddhant with the help of our relatives but he could not be traced. Finally, we decided to report the matter to the police on Thursday," Rai said.

Kishanganj superintendent of police Rajiv Ranjan said two friends of Siddhant have been detained. "Siddhant, along with his friends, had gone to Panjipada, a red light area, under the jurisdiction of Bengal police," he said. The victim's friends revealed to the interrogators that they fled from the red light area after a police team conducted a raid on Wednesday night. However, Siddhant was left behind and was suspected to have been caught. The friends, however, did not inform Siddhat's family.

Panjipada is close to Kishanganj border with Bengal. Kishanganj sub-divisional police officer Kamini Bala said a police team had been sent to Bengal to verify the statement of the victim's friends. She, however, admitted that a kidnapping case has been lodged on the statement of the victim's father.

In another development, two alleged extortionists - Angad Sahni and Dayal Sahni - were nabbed by the employees of a private construction company in Muzaffarpur when they had gone to collect extortion from the base camp of the company, RK Constructions Private Limited, at Paroo on Thursday.

Both the extortionists were later handed over to the police. One country-made pistol and four live cartridges were recovered from the possession of the arrested criminals.

The police, on the other hand, made a breakthrough in the daylight murder of two engineers in Darbhanga after the arrest of Rishi Jha and Subodh Dubey on Wednesday night, said to be close associates of Mukesh Pathak, one of the main accused in the case. The arrests were made from Bettiah in West Champaran. Rishi's arrest is considered a big achievement for the police.

The special task force (STF) nabbed Manoj Singh, a notorious gangster and chief of a criminal gang, Azad Hind Fauz, from Bairia in Muzaffarpur. The police also recovered a sophisticated weapon from Manoj, who was facing over 70 cases of murder and extortion in Muzaffarpur, Sitamarhi, Sheohar, East Champaran and West Champaran districts.

Inspector general (operations) S.M. Khopade said a special team consisting of the personnel of the STF and the district police of four districts has been assigned to nab the remaining members of the Santosh Jha gang.