The batsman led India to their famous victories in 1971 and overall scored 2,113 runs in just 37 Test matches, including one century.
Former Derbyshire batsman and qualified solicitor Tim O'Gorman is heading the investigation.
Stead, 46, was a journeyman opening bat, playing just five Tests in 1999 before being dropped.
A jury on Tuesday unanimously decided in less than three hours that Stokes was not guilty as was his co-defendant Ryan Ali, who was knocked unconscious in the brawl.
Electing to bat in the only T20 match of the tour, South Africa were bowled out for 98, a total the hosts surpassed with four overs to spare.
His wife, Clare, cried when the not guilty verdicts were returned while Stokes closed his eyes with relief and then looked up.
Anderson made the most of helpful conditions with a match haul of nine for 43 as England overwhelmed India by an innings and 159 runs.
The 29-year-old was suspended for a year and stripped of the captaincy by Cricket Australia.
Fellow pace-bowling all-rounder Chris Woakes, who took Stokes's place, starred with both bat and ball in a man-of-the-match display at Lord's.
The Bangladesh Cricket Board partially lifted his ban in 2016, allowing him to play domestic first-class and List A cricket.
Several cricket legends in the country have successfully switched to politics.
The tourists lost by an innings and 159 runs to go 2-0 down in the five Test series.
The overcast conditions and green-tinged pitch, as much a consequence of a sudden change in the weather after a prolonged dry spell as anything else, were ideal for Anderson.
Victory, achieved on the fourth day of a rain-marred match featuring a total first-day washout, put England 2-0 up in this five-match series.
With the brilliant innings from Mathews, backed by Niroshan Dickwella's 43, Sri Lanka made 299 for eight off their 50 overs.
