Mukhtar Ahmed Azmi, 75, along with his son and grandson, was about half way home on 6 September when unknown assailants on motorcycles opened fire on them in Pakistan's largest city, Karachi. Only Azmi's grandson survived.

This is just one of many unsolved murder cases in the city.

Karachi has had a long history of volatility stemming from sectarian, ethnic and political strife. Political parties fighting each other for control have drawn the city into a spiral of violence in recent years, a trend which seems to be getting worse. Eight people, linked with different political parties, were killed just this week.

One thousand seven hundred people were killed in Karachi between January and August 2012. According to the Human Rights Commission of Pakistan (HRCP), at least 1,345 of these murders were politically motivated - a dramatic increase on last year. The police say 1,244 killings between January and July 2012 were politically motivated.

"The ongoing killings are multidirectional," Sharfuddin Memon, security adviser to the government of Sindh Province, told IRIN. "Largely, the killings are of a political, ethnic or sectarian nature and then in some cases personal scores are settled."

According to police statistics, there were 60 sectarian killings between January and August 2012, with both Shias and Sunnis targeted. While sectarian killings are relatively small in number, they often receive more media attention.

"I think that, proportionately, the sectarian killings are quite low in the overall killing spree in the city this year. But they get media attention as the targeted personalities are usually prominent," said Idrees Bakhtiar, deputy editor of the Herald newspaper.

The growing number of killings has caused widespread alarm, and life is cheap, according to Fateh Mohammad Burfat, professor of sociology at Karachi University. "A target killer fee ranges between 5,000 [US$53] and 500,000 [$5,282] rupees."

What are the origins of the violence?

Much of the violence can be traced back to the regime of military dictator Zia ul-Haq who toppled the government of Zulfiqar Ali Bhutto in 1977 and radically transformed society.

Pakistan became a breeding ground for Islamist propaganda; many young people were recruited and trained to fight alongside the Mujahedin in Afghanistan. When they returned, they brought their weapons and fighting skills with them.

Drugs, especially heroin, became a major source of income for religious militias in Pakistan at this time.

"Till the late 1970s, our society was quite enlightened, progressive and liberal," said Burfat. "Even a single murder would have sensationalized the whole city in those times. But afterwards, the gun was made the symbol of power, and the political party considered most powerful was the one brandishing the most weapons," the sociologist said. Karachi's university campuses became battlegrounds for open conflict between secular and Islamist students, the latter obtaining weapons en route to Afghanistan.

In the mid-1980s, this low-intensity conflict gave way to more deadly confrontations. After an operation by the security services allegedly to control criminal activity in an area where many Pashtoons lived, ethnic Pashtoon mobs financed by drug barons attacked the city's Urdu-speaking majority (Muhajirs) in Karachi: Hundreds were killed in the December 1986 Aligarh massacre.

What is prompting the current killings?

"There is a complex political divide in Karachi and the monetary stakes are very high," said Zohara Yusuf, the HRCP chairperson.

Killing sprees tend to come in the wake of the arrest of hundreds of political and sectarian activists by the police, though such arrests rarely lead to convictions. "There is only a 5 percent conviction rate in criminal cases, and as trials can last for years, 90 percent of jail inmates are currently under trial," Burfat said.

Observers believe the current situation is tantamount to a breakdown in law and order.

"We have to admit that this is a failure of the state," Burfat said, adding: "All the political parties should recognize this harsh reality if they feel any responsibility towards the nation."

Sectarian rifts, gang wars, drug peddling and land-grabbing flourish in a city in which political parties draw their support from specific ethnic groups.

"Land grabbers and drug barons have taken shelter in political parties and become an integral part of the political culture," said Tauseef Ahmed Khan, head of the Mass Communications Department at the Federal Urdu University and a political analyst.

Who are the main players?

Muttahida Qaumi Movement (MQM) - MQM, currently the fourth largest party and a key ally of the ruling Pakistan Peoples Party (PPP), came to prominence in 1984 as the sole representative of the Muhajirs. Financed by local industrialists, it became a formidable political force. In 1992 (on orders from then President Nawaz Sharif) and 1995 (on President Benazir Bhutto's orders) the army and the paramilitary Rangers tried to shut down the party. The government claimed on both occasions that MQM was trying to establish an autonomous state in Karachi. During these years the government sponsored the emergence of a splinter group - MQM Haqiqi - in an attempt to weaken and outflank MQM. Since that time, MQM has tried to portray itself as a more inclusive, national party, but there are ongoing tensions with other ethnic groups, mainly Pashtoons. Some suspect MQM of being responsible for some of the killings of MQM Haqiqi members.

MQM Haqiqi - Emerged in 1992 during the military operation against MQM. MQM Haqiqi captured MQM's offices and tried to replace it, but failed to secure sufficient public support. It survives in some parts of the city and is thought to be behind some of the killings of MQM members. It has no MPs.

Awami National Party (ANP) - A secular party and key ally of the PPP government in Islamabad and the provincial government in Khyber Pakhtunkhwa. It draws most of its support from ethnic Pashtoons, who are the second largest group in Karachi after the Muhajirs. The Aligarh massacre, committed by Pashtoons, is the reason for the ongoing enmity between the two communities and their respective parties.

Sunni Tehreek - A political group of the Barelvi Sunni Sufi order, without any seats in parliament. Most of its members are said to be former MQM Haqiqi activists and are thus at loggerheads with the MQM. Tehreek activists are often accused of extortion.

Peoples Aman Committee (PAC) - Dominated by the Baloch ethnic group, PAC was formed in Lyari District, western Karachi. Unlike the rest of Karachi, which is mainly pro-MQM, Lyari District is dominated by the PPP. Allegedly PAC used to be a militant wing of the PPP, but the PPP withdrew its support in 2011. PAC was founded by local mobster Rehman Dakait and is now led by criminal kingpin Uzair Baloch. Allegedly it is involved in the weapons' trade and runs illegal gambling dens. It has been involved in deadly clashes with the MQM over control of some suburbs. PAC was officially disbanded in March 2011, but continues to function.

Pakistan Peoples Party (PPP) - The main ruling party which often has differences with MQM (its key ally). MQM blames PPP of using PAC as a proxy.

Katchi Rabita Committee (ERC) - Rivals of PAC, the ERC is dominated by ethnic Katchis and has a strong following in Lyari. Some say ERC receives tacit support from MQM to counter the PAC, a claim MQM denies.

Sipahe Sahaba Pakistan (SSP) - A Sunni extremist group banned by the government for its alleged Al Qaeda ties. SSP supports the killing of Shiites whom it believes are infidels. It has no formal HQ.

Sipahe Mohammad - A banned militant Shiite youth group believed to have carried out revenge attacks against SSP.

Tehreek Taliban Pakistan - Extremist Islamist group which uses Karachi as a base for its Waziristan operations. Known to have targeted ANP activists.