DENVER -- The 7NEWS Investigators have obtained copies of a police report showing that Denver police had the suspect in the officer's shooting in custody exactly one month ago but no charges were filed.

The Denver district attorney said the evidence was not strong enough to likely gain a conviction against Brian A. Washington.

According to the police report, on Aug. 20, exactly a month before he allegedly shot and killed Aurora police Detective Mike Thomas, police stopped a vehicle at the intersection of East Colfax and Xenia.

Police said that inside the car was Washington and a Browning 9-mm semi-automatic weapon with 12 rounds of ammunition. Police also found what they described as a large bag of marijuana, 7NEWS reported.

The police report acknowledges Washington's status as a previous offender apparently in possession of a weapon, but after reviewing the facts the district attorney elected not to pursue charges.

A spokeswoman for the district attorney said, "There was no reasonable likelihood of conviction."

The district attorney's office said there was a gun in the car, and according to the report it was near Washington, but Washington did not own the vehicle and was not the driver. Those facts make a conviction problematic.