More than 20 high specialized arson investigators from the ATF's National Response Team have been working on the cause of last weekend's fire.
The ATF has officially ruled that the 6-alarmer was arson, and is offering a $5,000 reward.
The ATF did not release any specifics about how the fire was set, just that it is arson, and is being investigated as a crime.
The agency is asking for the public's help by offering a reward and has set up a hotline.
"1-888-ATF-FIRE. People that have information related to that arson fire can call that line, and we will follow any leads," explained Special Agent Matt Horace.
The 6-alarmer broke out on Sunday around 5:50pm at the former Concord Chemical Company site at 17th and Federal. It was a superfund site that had recently been cleaned up at a cost of over $1 million.
It was the third major building blaze in Camden in 10 days, but officials say the 12-alarmer from June 9th, the 8-alarm fire two days later together, and Sunday's fire are not being compared. However the investigations are on-going.
"All of the agencies represented are talking every single day about things that may be associated with this fire, and the problem that it presents being arson. So we are talking every day, we're going to evaluate every lead until we determine who is responsible," said Special Agent Horace.
With 3,000 vacant buildings in Camden, the task of keeping people out is daunting for law enforcement.
"It is a monumental task, but it is something that we are doing. We are being as proactive as we can with the resources that we have," said Chief Scott Thomson.
Again the ATF is offering a reward of up to $5,000 for information leading to an arrest and conviction. Anyone with information is asked to call 1-888-ATF-FIRE.
