Human rights workers say they fear for the immediate safety of Aasia Bibi, the Christian woman at the heart of Pakistan's blasphemy furore, following the assassination of Punjab governor Salmaan Taseer this week.

"None of us feel safe, least of all her," said Shahzad Kamran, a Christian charity worker who has visited Bibi in jail several times since last November when she was sentenced to hang for blasphemy.

Bibi, a mother of four who has been sentenced to death for allegedly insulting the prophet Muhammad, has been in solitary confinement for the past month. But since Taseer was shot multiple times by his own guard in Islamabad on Tuesday, Kamran said he feared Bibi could be killed by a zealot.

"There are many chances. The prison guards could also kill her because they are Muslims and we cannot trust them," he said.

Kamran said he expected that Bibi's "heart was broken" at the death of Taseer, her most prominent defender, and that her plight had reverberated across Pakistan's embattled Christian community.

"Taseer died for the Christians and now we are feeling broke and scared. If they can kill the governor of Punjab then who am I?"

At least 10 Pakistanis have been killed while awaiting trail on blasphemy charges since 1990, according to human rights workers, including one man in Lahore last summer.

In Rawalpindi, Mumtaz Qadri, the rogue policeman who killed Taseer, made his second court appearance amid chaotic scenes. An armoured car drove him to a makeshift court in Islamabad where seminary students and lawyers showered him with rose petals.

Seeing the size of the crowd, police tried to move Qadri to a makeshift court in nearby Islamabad. But the plan was scuppered when Qadri supporters blocked a judge from leaving the building. The hearing took place seven hours late amid tumultuous scenes.

Qadri, who shot Taseer at least 17 times before surrendering, was bundled into the court wearing a black hood but emerged amid cheers with his head exposed. The judge ordered a medical examination. He was remanded until 10 January.

Qadri told interrogators he killed Taseer because the governor wanted to reform the controversial blasphemy laws used to imprison Aasia Bibi and hundreds of other minority Pakistanis. Taseer had called the legislation a "black law".

In Lahore political leaders paid their respects to Taseer's family at the sweeping governor's house amid tight security. The death of the flamboyant politician has exposed alarming rifts in Pakistani society, with many hailing the assassin as a hero.

It has raised serious questions about the integrity of the security services, and the vetting procedures for those guarding the country's most powerful figures. Qadri's extremist views were well known and had caused a senior officer to remove him from VIP duty last year, according to several reports.

The officer, named by Reuters as Nasir Durrani, reportedly described Qadri as a "security hazard" in a letter to the Punjab home department. Durrani is heading a joint police-intelligence investigation into Taseer's killing.

It is unclear why Qadri was reinstated to guard Taseer or why his fellow guards did not open fire once the attack started. Police have detained a dozen other people, including six police officers accused of abetting the assault.

Human rights workers fear that the focus on Qadri's trial will jeopardise Bibi's chances of a fair appeal hearing at the Lahore high court. "The debate has gotten very difficult," said IA Rehman of Pakistan's human rights commission.

"People are afraid of talking about the issue and the debate will affect the minds of the judges, who are themselves very conservative."

The furore comes at a delicate time for the ruling Pakistan People's party, of which Taseer was a member. The prime minister, Yousaf Raza Gilani, has just reversed a planned fuel price increase in an apparent bid to win back coalition partners who deserted the government last weekend.

The climbdown highlights the precarious position of the minority government. But divisions inside the opposition suggest that a midterm election is not imminent.

• This article was amended on 11 January correcting the killer's name to Mumtaz Qadri after we mistakenly gave his first name as Mustafa