A top homeland security lawmaker has called for an investigation into possible cyber attacks on computer systems at the Homeland Security Department.

Rep. Bennie Thompson, D-Miss., said he believes Unisys Corp — the Blue Bell, Pa., company that holds the $1.7 billion contract to build parts of the Homeland Security Department’s computer network — is at fault for these network break-ins. Thompson chairs the House Homeland Security committee and asked the department’s inspector general to investigate.