In a news conference Thursday, Boulder County District Attorney Michael Dougherty said he believes high-capacity gun magazines used in March’s supermarket attack were sold legally. 

But in 2013, following the Aurora theater massacre, Colorado’s legislature banned magazines holding more than 15 rounds. And charges against the Boulder suspect include 10 counts of using a prohibited high-capacity magazine while committing a felony.

So how might the suspect have gotten ahold of the 10 prohibited magazines the DA said investigators found on him or in his car? A handful of possible ways, it turns out. 

? Colorado’s law bans the sale, transfer and possession of magazines holding more than 15 rounds 

It went into effect on July 1, 2013. Known as House Bill 13-1224 while it worked its way through the legislature, the large-capacity magazine ban was part of a package of gun restrictions that also implemented a universal background check requirement for purchases and required buyers to pay the background check fee. In reaction, voters successfully recalled two Democratic state senators who supported the laws, Sen. John Morse of District 11 and Angela Giron of District 3. 

? DIY assembly kits have provided a loophole in Colorado 

An employee at Centennial Gun Club was captured saying, “As soon as we remove the functionality of it and take this spring out, it’s not a magazine.” Another at Pueblo Sporting Goods called the kits “technically legal – technically not illegal.” 

Sen. Rhonda Fields, who sponsored House Bill 13-1224, called businesses taking advantage of the loophole “sickening” and contrary to the law’s intent. But to date, the legislature has not passed further legislation to address the gap. 

? The states bordering Colorado don’t have large-capacity magazine bans 

Although possession of high-capacity magazines isn’t legal in Colorado, someone wishing to smuggle them in could hop a border to a dealer in any state immediately surrounding Colorado that sells large-capacity magazines. According to a compilation from the National Conference of State Legislatures, Wyoming, Utah, New Mexico, Arizona, Oklahoma, Kansas and Nebraska are not among the nine states with bans on high-capacity magazines.

? The law grandfathered in high-capacity magazines owned before the ban 

It allows high-capacity magazines a person possessed on or before the date the law went into effect and has continually maintained possession of. 

High-capacity magazines manufactured in Colorado on or after the law’s effective date have to include a permanent marking indicating its manufacture or assembly after July 1, 2013. The marking has to be visibly engraved or cast on the outside of the magazine. Violation of this part of the law is a Class 2 misdemeanor. 

? When a Clinton-era ban on some semiautomatic assault weapons and high-capacity magazines expired in 2004, it left a patchwork of state laws 

The Public Safety and Recreational Firearms Use Protection Act passed as part of the Violent Crime Control and Law Enforcement Act of 1994, and then-President Bill Clinton signed it.

The law banned the manufacture, transfer or possession of semiautomatic assault weapons and manufacture of magazines holding more than 10 rounds, though it grandfathered in possession and sale of covered weapons and magazines legally made and possessed before the effective date.

The law did not outright ban semiautomatic guns. Instead, it banned some specific firearms and certain features on guns.

But the ban expired in 2004 because of a sunset provision, and attempts to renew it have failed. Currently nine states and the District of Columbia have some form of ban on large-capacity magazines. The restrictions range from up to seven rounds in New York to maximum 15 rounds in Colorado, New Jersey and Vermont (for handguns in the latter’s law).