The family of Harry Dunn has called for Julian Assange not to be extradited as long as the US refuses to send the suspect in the teenager's death back to the UK.
The 19-year-old's parents have said they believe any further extradition requests by the US should be refused after US Secretary of State Mike Pompeo rejected the return of the woman involved in their son's death, Anne Sacoolas, last month.
Their spokesman Radd Seiger said the Foreign Affairs Committee had accepted their request for an inquiry into the extradition, and to the diplomatic immunity granted to Mrs Sacoolas.
Earlier this month, the Foreign Office said they had "no plans" to launch a public inquiry into the case - saying the case had been handled "properly and lawfully throughout".
The teenager was killed when his motorbike crashed into a car driven by Mrs Sacoolas outside a US military base in Northamptonshire on August 27 last year.
Mrs Sacoolas, the 42-year-old wife of an intelligence official based at RAF Croughton, was granted diplomatic immunity after the crash and sparked international controversy after being allowed to return to her home country.
She was later charged with causing Mr Dunn's death by dangerous driving.
Mr Dunn's mother, Charlotte Charles and father, Tim Dunn, said they were told by Foreign Secretary Dominic Raab that the Government was "reviewing all our options" after Mr Pompeo's refusal to extradite Mrs Sacoolas.