Transcript for New details on the Stockholm truck terror suspect

We have an update on the terror attack in Stockholm. Authorities revealing new information about the man who allegedly stole a truck and turned it into a deadly weapon. Raising questions about whether warning signs were missed. Here's Jennifer Eccleston. Reporter: New details about the suspected thrive -- driver of this stolen delivery truck. Police revealing they tried to deport him just six weeks ago. He was applying for residence. That was rejected. Reporter: But when police went to his home to deport him, they couldn't. He had given them the wrong address. The unnamed suspect, also known to intelligence services in the past. Determined a marginal player. But tonight police revealing he showed ISIS sympathies. The suspect, arrested just hours after the attack. Another suspect also in custody. Police beefing up patrols across the capital. Over 500 questioned. Thousands today gathered at the scene of the attack to remember the four killed. From Sweden, Belgium, and from the uk. 41-year-old father Chris Bevington. A music executive based in Stockholm. Questions about Sweden's extremist monitoring, and how the suspect slipped through their net before committing one of the country's worst acts of

This transcript has been automatically generated and may not be 100% accurate.