After a week of silence and speculation, former Sioux Falls Fire Chief Jim Sideras was arrested Monday, charged with possessing child pornography.

State police and county deputies removed CDs, hard drives and computers from the fire chief's home last Tuesday, hours before his employment with the city was abruptly terminated. He was scheduled to retire next month.

The search was triggered by a tip from the National Center for Missing and Exploited Children, which received information that a suspect in a Massachusetts child pornography investigation had sent images to an email address later linked to Sideras.

According to an affidavit filed in support of the search warrant, investigators traced the email account, registered under the name Sandi Johnson, to a Midco IP address assigned to Sideras' home at 4408 S. Magnolia Drive in Sioux Falls.

►Previously: What we know about Jim Sideras investigation

The same email account was also accessed from a San Antonio hotel on dates that Sideras tweeted from a firefighter accreditation ceremony there, the affidavit says.

The South Dakota Internet Crimes Against Children Task Force sought a search warrant of Sideras' property, including his home and two vehicles.

Attorney General Marty Jackley and Minnehaha County Sheriff Mike Milstead, whose offices executed the search, declined to comment for days on the reasons for the raid. Mayor Mike Huether also declined to give specifics on why Sideras was let go.

Sideras had been the face of Sioux Falls Fire Rescue for years. He was promoted to fire chief in 2011 after several years as the department's spokesman. He once hosted a regular informational fire safety program for the city.

He joined the department in 1983 and had just announced his upcoming retirement at an event in April.

Division Chief Brad Goodroad, who was named interim fire chief last week, did not respond to a request for comment Monday. The city issued a statement after Sideras' arrest saying officials had no knowledge of his alleged actions.

►Previously: Firefighters warned against contact with ex-chief

"This has been extremely troubling from the onset, and the charges outline why this process is being handled in such a cautious and deliberate fashion," Huether said in the statement. "This is terribly unfortunate, but Sioux Falls Fire Rescue has been top notch at saving lives and protecting property, and we won't skip a beat executing it now."

City Councilor Pat Starr said he was shocked and disappointed to learn about the charges. He and other councilors said they were in the dark last week.

“I’m thankful that, if this did happen, that there are investigators taking care of this kind of thing,” Starr said. “It makes me sick in my gut, but we always have to remember you’re innocent until proven guilty.”

Sideras is charged with 10 counts of possession of child pornography. He faces up to 10 years in prison for each charge if convicted. His case will be prosecuted by Minnehaha County State’s Attorney Aaron McGowan.

“I'm not able to share any details beyond the affidavit," McGowan said Monday.

Sheriff Milstead said his office contacted Sideras' attorney Monday, and that Sideras turned himself in, then posted bond before being released.

His bond was set at $10,000 cash or surety.

Sideras did not return phone calls or answer his door Monday.

Casey Murschel, a coordinator for the Child Advocacy Centers of South Dakota, said high-profile child pornography cases force the community to have a conversation around an unpleasant topic.

“When situations come to light, such as this, I think if there’s any value, it is raising the public’s awareness," Murschel said. "As much as we would like to think it doesn’t happen here, it does."