Fiona Onasanya is expected to become the first MP to vote in the Commons while wearing an electronic tag after being released from prison.

The MP for Peterborough could return to parliament for a crucial Brexit vote on Wednesday after serving a month of her sentence for perverting the course of justice.

Onasanya, who has been expelled from the Labour party, left HMP Bronzefield in Ashford, Surrey, on Tuesday morning.

The former solicitor was jailed for three months at the Old Bailey on 29 January after repeatedly lying to avoid a speeding charge.

She was released after a month after agreeing to wear an electronic tag and observe a curfew, sources said. She is appealing against her conviction at a hearing scheduled for 5 March.

Associates believe that Onasanya, who voted for remain in the EU referendum, may return to parliament this week. She insisted before she was jailed that she would continue to represent her constituents while maintaining her innocence.

She has voted 12 times in the Commons since her conviction on 19 December. On eight of those occasions she voted on the government’s Brexit plans, including voting against Theresa May’s Brexit deal in January.

Whether she is able to vote on Wednesday will depend in part on the terms of her curfew. The vote is expected to be held at around 7pm.

Onasanya, 35, sat in the back of a white Vauxhall with the closest window to her covered by a hi-vis jacket as it drove past photographers.

She continues to sit as an independent MP, despite calls for her resignation. Under parliamentary rules, a prison sentence of at least 12 months is required for the automatic removal of an MP. A lesser sentence can result in a recall petition, however, which would result in a byelection if it is signed by more than 10% of the electorate in the constituency.

It emerged on Tuesday that two police forces are investigating racist emails and letters sent to Onasanya. Cambridgeshire and South Yorkshire police have been asked to examine “malicious communications” sent to her office, the Peterborough Telegraph reported.

Onasanya’s communications officer, Matt Turner, said: “Many of these emails and letters have a disgusting racial element to them.”

Jurors at the Old Bailey were told Onasanya had colluded with her brother Festus after her car was clocked at 41mph in a 30mph zone in the village of Thorney near Peterborough in July 2017.

She was sent a notice of intended prosecution to fill out, but it was sent back naming the driver as Aleks Antipow, an acquaintance of her brother, who was away visiting his parents in Russia.

Festus Onasanya was sentenced to 10 months in prison after he pleaded guilty to three counts of perverting the course of justice over speeding, including in relation to the 24 July incident.

The attorney general’s office ruled that Onasanya’s sentence was not unduly lenient, after a complaint was lodged.