India's unsolved bombings
A series of bombings. No claim of responsibility. No prime suspects.
Wednesday's explosions in India's financial capital Mumbai ticked a wearily familiar list of boxes in a country which is no stranger to bombings that go unclaimed and lack any transparent motive.
Briefing reporters on Thursday about the investigation, Home Minister P. Chidambaram cast the net of suspicion about as wide as it would go.
"All groups hostile to India are on the radar. We are not ruling out anything, we are not ruling in anything. We are looking at everyone," he said.
"Whoever perpetrated the attack has worked in a very callous manner. Maybe it's a very small group working in a clandestine manner," he added.
Chidambaram's remarks were partly aimed at pre-empting the knee-jerk accusations of Pakistani complicity that invariably surface after any act of terror in India.
New Delhi has long accused its arch-rival and neighbour of aiding and abetting the militant groups who have carried out attacks on Indian soil, including the traumatic 2008 assault on Mumbai by Islamist gunmen that claimed 166 lives.
But his comments also highlighted the information vacuum which all too often surrounds seemingly arbitrary incidents.
There were several such attacks last year, including a blast at a packed restaurant in the western city of Pune which killed 16 people including several foreigners.
Low-intensity twin explosions wounded around a dozen people at a cricket stadium in Bangalore and a girl was killed by a bomb at a religious bathing site in Hinduism's holiest city of Varanasi.
In September, two Taiwanese men were shot outside Delhi's main mosque, while most recently, a crude device planted outside the Delhi High Court in May failed to go off after its detonator malfunctioned in the fierce summer heat.
None of these cases has been solved. There were no claims of responsibility and it is not even confirmed that they were part of a terrorist strategy, with suggestions that at least one may have been part of a criminal vendetta.
Given the lack of a proven suspect or tangible motive, politicians and the media tend to fall back on vague notions of terrorist intent.
Wednesday's Mumbai blasts were "an attack on the heart of India," said the chief minister of Maharashtra state, Prithviraj Chavan.
"India is under assault," the Times of India said in an editorial on Friday, adding immediately: "One doesn't know yet who is responsible."
The idea of "India" as the target inevitably implies the possible involvement of elements from arch-rival Pakistan, and numerous commentators noted that the blasts occurred just before scheduled peace talks between the Indian and Pakistani foreign ministers later this month.
A favoured suspect is the Indian Mujahideen, a homegrown group with links to Lashkar-e-Taiba, the Pakistan-based militant outfit blamed for the 2008 Mumbai attacks.
The Indian Mujahideen were behind a series of bombings in Indian cities in 2008-09, but their past operations have been marked by a swift claim of responsibility.
Some security analysts say that the police, in the absence of any hard evidence, have often attempted to build false cases to conceal the lack of progress in recent cases.
"This is the standard routine," said Ajai Sahni, executive director of the Institute of Conflict Management in New Delhi.
"The police have no real forensic capability and they fabricate evidence all the time, and then go to the court with the wrong accused," Sahni told AFP.
Rakesh Maria, head of the Maharashtra state anti-terrorism squad, appealed Thursday for the public to have "faith and trust" in the police and promised that the perpetrators of Wednesday's bombings would be found.
But public sentiment was perhaps better reflected by Friday's newspapers, with headlines like "Police clueless" and "Government gropes in the dark."
By Giles Hewitt from AFP