Investigators inside the Zizzi restaurant in Salisbury, England, Tuesday, March 6, 2018 near to where former Russian double agent Sergei Skripal was found critically ill.  Britain&amp;#039;s counterterrorism police took over an investigation Tuesday into the mysterious collapse of a former spy and his daughter, now fighting for their lives. The government pledged a &amp;#034;robust&amp;#034; response if suspicions of Russian state involvement are proven. Sergei Skripal and his daughter are in a critical condition after collapsing in the English city of Salisbury on Sunday. (Steve Parsons/PA via AP)