Friends Ryan, 20 and 17-year-old Janis both died when violence flared in Doncaster town centre in the early hours of Saturday morning – with the bloodshed sending shockwaves across the town.
A 19-year-old has been arrested on suspcion of murder while two other men were also held by police on Tuesday.
It brings the number of arrests in the case to five and comes as grieving friends prepare for a number of emotional tributes to the pair this weekend.
The families of the two men killed in the incident at the junction of Silver Street and High Street have also paid touching tributes to former Doncaster Rovers Academy player Ryan and his pal Janis.
Heartbroken mum Lisa wrote: “You were my only son and such a mummy’s boy. You will always be with me in my heart forever and always.
"You will be sadly missed so much. Sleep tight and be with the angels.”
Janis’s sister Russanda Kozlovska wrote: “We’re all heartbroken - I've always seen things like this on the news but now it’s happened to my own family.
“They were both young lads with their whole life ahead of them.”
Police said a 19-year-old man had been arrested on suspicion of murder and remains in police custody.
Two men both aged 41 have also been arrested on suspicion of assisting an offender – and they have both been released under investigation.
A 17-year-old boy was arrested on Saturday on suspicion of murder and later released on bail and an 18-year-old man was arrested for a serious public order offence relating to the incident. He has since been released without charge.
The murder probe was sparked after a brawl outsided a bar in Silver Street at around 2.30am on Saturday, which also saw an 18-year-old taken to hospital with stab wounds. He has since been released and is recovering.
Police were called to reports of a serious altercation which spread into nearby High Street, near to the Danum Hotel.
Despite the best efforts of passing members of the public, police and paramedics, Ryan was sadly pronounced dead at the scene.
Janis was taken to hospital via ambulance but sadly later died from his injuries.
A subsequent post mortem examination has established that both Janis and Ryan died from stab wounds.
Large swathes of Doncaster town centre were sealed off throughout Saturday as one of the town’s biggest ever murder investigations got under way.
High Street, Silver Street, Scot Lane, Cleveland Street and Hall Gate were all closed for more than 18 hours as detectives pieced together the tragic events. Dozens of pubs and shops inside the cordon were also forced to close as the town centre fell eerily silent on what would normally have been a busy Saturday shopping afternoon.
A number of floral tributes have been placed at the scene of the killings and this weekend a number of emotional events will be held to remember the pair.
On Saturday, friends will gather at Elmfield Park at 3pm to release hundreds of balloons to remember the pair, while on Sunday, Ryan’s team mates from his former football club Bessacarr FC will take part in a fundraising charity football match at Cantley Park from 1.30pm.
A spokesman for Doncaster Rovers’ Club Doncaster Sports College said: “Club Doncaster Sports College are extremely saddened to hear about the passing of former student and Academy player, Ryan Theobald.
"Our deepest condolences go out to Ryan's family and close friends at this difficult time.”
And more than £7,000 has been raised for the families of the pair through a series of crowdfunding pages HERE.
Police are still appealing for witnesses with information about the incident to come forward – and have promised to step up security in the town centre in the wake of the tragedy.
South Yorkshire Police has said that there will continue to be an increased presence of officers, while further knife arch operations will also take place.
People have also been urged to pass on details of individuals they know who carry knives – and pass on information relating to all forms of knife crime.
Chief Superintendent Ian Proffitt said: “There continues to be an increased presence in Doncaster town centre following the murder of two men on Saturday.
"We know that incidents like this can have a devastating impact, not just on the families affected but on the wider community too.
“I want to assure you that improving safety in Doncaster town centre continues to be a priority for us.
"Our officers, along with partner agencies, have been working together over recent weeks to clamp down on crime and antisocial behaviour in the town centre.
"As part of our plans we already have officers from our dedicated tasking team and Operational Support Unit who along with our local Neighbourhood Team regularly run knife arch operations and patrol the town centre to try and prevent incidents like this.
"However, sadly, we know that they can still happen and people still continue to carry knives.
“We need your help and support to prevent crimes like this. If you have concerns about anything you see in Doncaster town centre, or know somebody that carries a knife please continue to report it to us.
"We will listen and can help. With your support we can hopefully try and prevent incidents like this from happening again.”
Police have urged anyone with any information about the events of Saturday night to come forward.
A spokesman said: “We still want to hear from anybody who may have saw what happened or captured any footage of the altercation , which started in Silver Street and continued into High Street, ending outside the KFC.
"Information can be passed onto police by contacting 101 and quoting incident number 135 of 29 January, or you can give information anonymously to independent charity Crimestoppers via their website – www.crimestoppers-uk.org – or by calling their UK contact centre on 0800 555 111.
You can also provide information directly to the investigation team via the Major Incident Public Portal HERE.