The two brothers who helped carry out the attacks in Brussels this week that killed dozens and wounded hundreds reportedly were also involved in the secret videotaping of a Belgian nuclear scientist, a development that has raised fears the extremists were seeking to secure radioactive material for a dirty bomb.

Reports surfaced in February that a police search of the apartment of a suspected participant in the November Paris attacks yielded roughly 12 hours of video footage surveilling the home of the director of research for the Belgian nuclear program. The footage is now believed to have been recorded by Ibrahim and Khalid El Bakraoui, according to information obtained by Belgian newspaper Derniere Heuere.

Brothers Ibrahim El Bakraoui, top, and Khalid Bakraoui, below.

Belgian Federal Police/Interpol/AP

Authorities speculated that extremists may have been plotting to kidnap the scientist and attempt to use him to infiltrate a nuclear research facility. The surveillance video includes footage of the director's front door and a local bus stop.

Jan Jambon, Belgium's interior minister, told the parliament that the ministry determined there was a threat to the person, not the nuclear facility, according to a February report in The Independent, raising concerns that the attackers may have planned to use the director to secure radioactive material in order to build a dirty bomb.

In response to reports about the suspected plot to access a nuclear facility, Belgium added military guards to its nuclear power plants. A Belgian prosecutor reportedly insisted on not releasing the identities of those involved for security reasons and to avoid endangering the subsequent inquiry.



The brothers – both of whom died in Tuesday's suicide attacks – targeted an airport and a subway station after their suspected accomplice, Salah Abdeslam, was captured in Brussels last week.