LAKEWOOD, Colo. -- A Glenwood Springs man whose DNA linked him to four sexual assaults in Boulder has been formally charged in a Lakewood case.

Bradford Thomas Wagner, 36, already in custody in the Boulder cases, was charged Wednesday with four counts of first-degree sexual assault in connection with a 1994 rape in Lakewood.

He was being held Thursday in Boulder on $1 million bond.

Authorities in the 1st Judicial District were waiting for a judge to sign an arrest warrant for the Lakewood case, said Aura Leigh Ferguson, spokeswoman for the District Attorney's Office.

Two years ago, DNA tests linked six rapes to a single suspect. Four violent sexual attacks from 1993 to 1998 in the Tantra and Bridgewalk apartment complexes of Boulder, the rape in Lakewood, and another in Austin, Texas, were all traced to one man.

Detectives then began an exhaustive computer search of public and commercial databases looking for the man who was living in Boulder, Lakewood and Austin during the times of each of the sexual assaults.

That search caused police to suspect Wagner.

Last month an undercover Boulder police officer, posing as a potential real estate client, surreptitiously collected DNA samples from Wagner, his car, his home and his bicycle. The Colorado Bureau of Investigations said tests showed it matched DNA gleaned from the Boulder rapes.

Wagner's attorney Wilbur Smith said Wagner is innocent.

"DNA is far from perfect," he said. "There have been incidents recently where people have been accused and falsely convicted by bad DNA tests. This case is not as open and shut as the prosecution and police would lead you to believe."

Smith also said police may have violated Wagner's constitutional rights when the DNA was collected without his knowledge.

Wagner was arrested June 12 at his home in Glenwood Springs in connection with the Boulder rapes. Prosecutors last week filed eight first-degree sexual assault charges against Wagner in those cases.

In two of those assaults, the victims said the man held them at knifepoint and verbally threatened them.

Wagner could be sentenced to life in prison if convicted.

Other cities, including Denver and Glendale, are submitting additional DNA evidence on unsolved rape cases that match characteristics of the Boulder assaults.

Public records show that Wagner has an extensive arrest record in at least six states.

Wagner was born in Bismarck, N.D. Records show that in the past 17 years he has lived in Boulder; Austin, Texas; Denver; West Hollywood, Calif.; Steamboat Springs, Aspen and Glenwood Springs.

Besides working in commercial real estate, he also taught snowboarding at Snowmass Ski Area the last two seasons.