Pakistani national Tashfeen Malik, 27, and her Pakistani-American husband Rizwan Farook, 28, had links with Maulana Abdul Aziz, the cleric of Pakistan's notorious Red Mosque of Lal Masjid, according to media reports.
The information about the links has been shared by US officials in London with Shahbaz Sharif, the brother of the Pakistani Prime Minister Nawaz Sharif.
Pakistani media also reported about the links between the suspected shooter and the radical Islamic cleric of Red Mosque.
"Tashfeen was in contact with Islamabad's Lal Masjid," a US official was quoted as saying by ARY News to an unnamed Pakistani official familiar with the investigation.
"Investigation officials have found Malik's pictures in which she can be seen with Lal Masjid cleric Maulana Abdul Aziz," it said.
In a statement, the Pakistani embassy here hoped that the investigations would lead the authorities to bring the perpetrators of this act to justice sooner.
However, it made no mention of any links between the suspected shooter and the radical Islamic cleric.
The Los Angeles Times reported that authorities in Pakistan are investigating whether Tashfeen had ties to Islamic militant organisations.
She had pledged allegiance to an Islamic State leader on Facebook, officals had said.
"Intelligence agents have questioned members of Malik's extended family in the province of Punjab, an area that is considered as one of the nurseries of militant organisations, according to Pakistani intelligence agents," the daily reported.
According to the report, Tashfeen belonged to an educated, politically influential family from Karor Lal Esan in Layyah district. Malik Ahmad Ali Aulakh, one of her father's cousins was a provincial minister from 2008-13.
"The family has some extremist credentials, and some members of Malik's family in Karor are also involved in sectarian activities," Zahid Gishkori, a local resident who knows the family well told the US daily.
Tashfeen's family was said to follow the Barelvi version of Sunni Islam, which is considered more into spiritualism than militancy.
"But sources said it was likely that she had converted to the Salafi/Wahabi version of Islam after spending most of her life in Saudi Arabia," the daily reported.
For the past several years, Congressman Ed Royce, who is now Chairman of the powerful House Foreign Affairs Committee, has been demanding that Pakistan shut down the 600 madrasas that preached radical Islam.