The chairman of the House Homeland Security said he’d like to see the Federal Bureau of Investigation step up its involvement in the Malaysia Airlines investigation now that all signs point to the flight being downed intentionally.

Sources close to the investigation told the Telegraph on Tuesday that signs point to the Boeing 777 being flown “in a rational way” inconsistent with catastrophic mechanical failure, and the probe is now focusing on intentional downing possibilities including pilot suicide.

Rep. Mike McCaul (R-Texas) dismissed the theory that lithium batteries in the cargo hold took down MH370, sparking a fire that somehow took out the electronics.

“The problem with that is, after the transponder is turned off and it reroutes the path, it flies for another seven hours. I don’t think it could withstand that kind of fire for seven hours and stay in the air. As we saw the UPS flight out of Dubai only lasted about 30 minutes,” he told Fox.

The FBI is still trying to retrieve deleted files from the pilot’s home flight simulator, the chairman added.

“I have every confidence they will be retrieved. I don’t know how key that evidence will be in this particular case. The one thing I’ve said all along, is I think this was an intentional deliberate act because of where it took place, and that’s after they went out of the Malaysian airspace and before the Vietnamese airspace, which is a dead zone,” McCaul said.

“The transponder was turned off, and then the plane dramatically turned around back toward Malaysia. Which has all the indicators of an intentional act. Now, what’s the motive behind this, we really don’t know. I’d like to see the FBI be little more involved with the Malaysian government. They’ve been very limited in the scope for their investigation and that’s really to the flight simulator.”

Despite the Malaysian prime minister’s announcement that everyone on the plane is dead, McCaul stressed “this is still a rescue operation, not recovery.”

“And that means that they still have some thoughts that they still may be possibly alive, debris may be found in the ocean. I think the way the Malaysian government has handled this has really been abysmal. And they texted the victim’s families rather than contact them in person. And if I could just backtrack, you know, when we had these two flight patterns, one to the north, one to the south, the Malaysian government was given days after the plane was missing intelligence from a satellite company, that it went southbound, not northbound. And yet the Malaysian government chose to spend a week looking in the gulf of Thailand up towards Kazakhstan. We knew because of the radar detection capability in China, India, Pakistan, Afghanistan that there’s no way this plane went northbound and yet, we wasted a week of valuable critical precious time on the northern route trying to find this plane instead of looking to where it went, that’s the Indian Ocean.”

McCaul said all along lawmakers have been briefed on intelligence indicating the plane took the southern route.

“Which is I think where the aircraft is today,” he said. “Probably sank to the bottom. And so, I, you know, this is an ongoing investigation, there are many theories out there, none connect all the dots at this point in time.”