WASHINGTON As an FBI team arrived in Pakistan to investigate the failed Times Square bombing in New York, a senior American law enforcement official said that Faisal Shahzad, the accused the case, had brought $80,000 in cash into the United States when he returned from overseas trips between 1999 and 2008. There is a lot of money, the official, who was not named, was quoted as saying in the course of a dispatch published in The Washington Post on Saturday. Meanwhile, political observers noted that the three-member FBI teams departure to Islamabad came as the Obama administration worked on the plans to expand US Special Forces troops in Pakistan. The FBI has a legal attachT office in Islamabad that works with Pakistani law enforcement and intelligence officers, The Post said, citing Pakistani officials. Pakistani cooperation is considered as crucial in nailing down the radical ties of Faisal Shahzad, the US citizen of Pakistani origin charged in the attempted bombing. Inside the United States, the investigators were interviewing people who might have ties with Shahzad, but no one is subject to imminent arrest, a senior official was cited quoted as saying. The newspaper said a key focus was the money trail. Investigators were tracking a money courier who may have helped funnel cash to Shahzad from overseas, but they cautioned that any links were uncertain. Shahzad also may have obtained money to fund the Times Square operation from a hawala, according to a former US official briefed on the investigation. Hawalas have been linked to al-Qaeda and other terrorist groups. Several days after his arrest, the dispatch said Shahzad continued to cooperate with interrogators, to the point where they keep returning to ask follow-up questions. One issue complicating the probe: Shahzad had multiple e-mail addresses. Investigators are trying to unravel thousands of messages, which in turn lead to more e-mails and web sites, officials said. Investigators continue to believe that elements of the Pakistani Taliban trained Shahzad, but they are uncertain about his claims to interrogators that he met higher-ups within the group, including Hakimullah Mehsud, US officials said. A senior Pakistani official said on Friday that no evidence has emerged of ties between Shahzad and Mehsud, but there are strong indications that Shahzad, during his trips to Pakistan, was in touch with Jaish-e-Muhammad. A federal law enforcement official said on Friday that Shahzad had listened to speeches by militant Islamic clerics in the years since the September 11, 2001, terrorist attacks. Among those Shahzad has cited as inspiring him is Anwar-al-Aulaqi, the American-born cleric in Yemen who has been tied to the suspect in the attempted Christmas bombing on a Detroit-bound plane as well as the man charged in last years fatal shootings at Fort Hood, Texas. Shahzad himself does not appear to have communicated with Aulaqi. In Pakistan, The Post said authorities have detained numerous militants, some of whom they think might be connected to Shahzad, as well as the fathers of both Shahzad and his wife. A Pakistani official said the Government is engaged in a hectic probe to nail down any ties that Shahzad may have had with militant groups in that country.