Federal authorities have accused Afghan-American terror suspect Najibullah Zazi of purchasing chemicals and equipment used to make homemade explosives, the same materials used in the 2005 bombings of London's subway and bus system, according to court documents made public on Thursday.

But, NEWSWEEK has learned, investigators have not yet recovered all the explosives components they accuse Zazi of purchasing. Two counterterrorism officials close to the investigation said recovery of the materials was part of the "ongoing investigation." NEWSWEEK reported earlier this week that investigators were looking for a possible bomb factory or cache of explosives-related materials as part of an investigation in Queens, N.Y., and the Denver area.

In a memorandum seeking the continuing detention of Zazi, who was arrested in Denver last week on charges of lying to investigators, federal prosecutors say that during July and August of this year, Zazi and unnamed "others associated" with him bought "unusually large" quantities of hydrogen peroxide and acetone products from beauty-supply stores in the Denver area. The Feds say that reference to these chemicals is made in notes, believed to be in Zazi's handwriting, which were found stored in the memory of a computer seized earlier this month from a car rented by Zazi. The notes allegedly describe how hydrogen peroxide and acetone can be combined with a strong acid such as hydrochloric acid to manufacture an explosive known as TATP, which was used in the 2005 London transport bombings as well as in the "shoe bomb" that Londoner Richard Reid unsuccessfully tried to detonate as he flew to the U.S. from Britain in December 2001.

The Feds say they have surveillance videos and receipts that indicate that on July 25, Zazi bought six bottles of a chemical called Liquid Developer Clairoxide from a beauty-supply house in Aurora, Colo., where he has lived with family members since earlier this year. The document says this product contains high concentrations of hydrogen peroxide. Zazi later purchased 12 32-ounce bottles of another peroxide-related product, Mrs K Liquid 40 Volume, from the same store.

The Feds go on to allege that unnamed "individuals associated with Zazi" also purchased "unusual" quantities of "hydrogen [sic] and acetone products" over the last three months from three different beauty-supply stores in Aurora. According to prosecutors, one unnamed person bought a one-gallon container of a product containing 20 percent hydrogen peroxide as well as an eight-ounce bottle of acetone. A second unnamed person bought an acetone product in early September. On around three occasions during the summer, the Feds say, a third person bought 32-ounce bottles of something called Ion Sensitive Scalp Developer, a product with high concentrations of hydrogen peroxide. During the course of investigations into the London transport bombings, British investigators discovered that alleged conspirators made similar purchases from beauty shops and beauty-supply wholesalers. Attacks on three subway trains and one double-decker bus on July 7, 2005, using backpack bombs packed with homemade explosives, killed more than 50 people, but a similar attempted attack two weeks later fizzled when the improvised bombs failed to explode.

In their court filing, which argues for Zazi's indefinite detention, the Feds say that earlier this month Zazi rented a suite at a hotel near his family home in Aurora, and that forensic examinations of the suite by the FBI turned up evidence of "acetone residue" in a vent above a stove. Prosecutors note that the alleged bombmaking recipes found on the computer in Zazi's car discuss heating up bomb components in order to make them highly concentrated.

Earlier this month, according to the Feds, before Zazi drove his rental car across country on a trip to New York, he tried to communicate on several occasions with an unnamed individual, "seeking to correct mixtures of ingredients to make explosives." Included in these communications, whose method of transmission is not disclosed, were "requests related to flour and ghee oil," which the Feds say are two ingredients listed in the handwritten bomb recipes. The Feds say that each of Zazi's communications with the unnamed associate was "more urgent in tone than the last."

The Feds also say that examination of Zazi's computer indicated that after attempting these communications with the unnamed associate, Zazi searched the Web for locations of home-improvement stores in Flushing, Queens. He then searched a home-improvement store's Web site, apparently to see if the store stocked muriatic acid, which the Feds describe as a diluted version of hydrochloric acid, which, along with hydrogen peroxide and acetone, would constitute a complete set of ingredients for homemade TATP. According to the Feds, Zazi looked at Web hits for four different types of muriatic acid, looking at one in particular—Klean Strip Green Safer Muriatic Acid, which claims to produce fewer fumes and to be safer to handle than other similar products—several times.

The Feds say that when they searched a residence in Queens where Zazi had stayed on his arrival from his cross-country rental-car drive from Denver, they found an electronic scale and batteries that had his fingerprints on them. The Feds say the scale could have been used to measure explosives ingredients according to the handwritten instructions found on Zazi's computer.

Zazi and his father, Mahommed, who lives in Aurora, were arrested late last week and charged with lying to investigators, but the father was later released on bail. A hearing had been scheduled for Thursday in Denver regarding whether the younger Zazi could be released on bail, a development that the government—alleging that evidence collected so far leads to an "inescapable conclusion" that a serious plot was afoot—strongly opposes.

In addition to producing the memo arguing that Zazi's detention should continue, the Feds issued a fresh criminal indictment against Zazi, charging him with "conspiracy to use weapons of mass destruction." The indictment gives no indication of any specific targets for such a conspiracy; investigators have noted the similarities between materials used in the London transport attacks and the materials Zazi and his unnamed associates allegedly collected, but have said they are not positive what if any targets Zazi might have chosen for possible attacks inside the U.S. Before his arrest, both Zazi and his lawyer had denied that he had any involvement with terrorism.