By Julia Love and Sharay Angulo
MEXICO CITY (Reuters) - A judge ordered a former Mexican Cabinet minister to be detained pending a trial over suspected losses to taxpayers, her lawyer said on Tuesday, opening a new front in President Andres Manuel Lopez Obrador's campaign to eradicate corruption.
The detention of former social development minister Rosario Robles is likely to ramp up scrutiny of the administration of Lopez Obrador's predecessor, Enrique Pena Nieto, whose 2012-2018 presidency was plagued by graft scandals.
Lopez Obrador has made rooting out corruption the cornerstone of his career, though he took office in December saying he did not want to rake through the past.
That upset some supporters of the president who felt he should be doing more to punish wrongdoing from previous governments. In recent months, investigators have begun to close in on some prominent figures in the last administration.
Lopez Obrador told his regular morning news conference he was aware of Robles' detention and said judicial authorities would decide whether others were implicated in the case.
"But it's not our business, and I'm not Pontius Pilate either," he said, referring to the Roman governor of Judea who oversaw the trial of Jesus.
Still, when asked whether the Robles case represented an achievement for his administration, Lopez Obrador said: "I believe it's an accomplishment that there is no impunity."
Prosecutors have accused Robles, a former party colleague of Lopez Obrador, of "improper exercise of public service."
Robles last week appeared in court over prosecution claims that more than 5 billion pesos ($258 million) destined for welfare programs during her tenure had gone missing at the ministry, according to local media reports.
The attorney general's office has declined to give details of the case, but the investigation has fuelled accusations that the money was siphoned off. Robles denies the allegations.
Julio Hernandez, a lawyer for Robles, said on local television that she will fight the accusations.
"Truly, Rosario Robles is innocent," he said.
Duncan Wood, director of the Wilson Center's Mexico Institute in Washington, said even if Lopez Obrador did not want to open a slew of corruption cases from the past, the onset of proceedings against Robles could make that harder.
"At some point, what's going to happen if evidence comes out that (Pena Nieto) was aware of these facts?" he said. "You have the makings here of a really explosive situation."
Trouble is already brewing for other prominent figures from the Pena Nieto administration.
In May, a judge issued an arrest warrant for the former chief executive of state oil firm Pemex, Emilio Lozoya, in a graft case involving Brazilian builder Odebrecht.
Allegations of wrongdoing have haunted Robles for some time, all of which she has denied. After giving up the social development portfolio under Pena Nieto, she served as the minister for agrarian, land and urban development.
A 2017 investigation by Mexican news site Animal Politico and nonprofit Mexicans Against Corruption and Impunity found that federal auditors had detected irregularities worth millions of dollars in the accounts of the ministries run by Robles.
A fixture in Mexican politics for two decades, Robles was the first female mayor of Mexico City, serving on an interim basis before Lopez Obrador became mayor of the capital.
Both of them also served terms as head of the Party of the Democratic Revolution (PRD), for years Mexico's main leftist party. Lopez Obrador later left and founded a new party.
Many on the left viewed it as a betrayal when Robles accepted a post under Pena Nieto, whose Institutional Revolutionary Party (PRI) ruled Mexico for most of the 20th century and eventually became a byword for corruption.
(Reporting by Julia Love and Sharay Angulo; Writing by Julia Love; Editing by Dave Graham, Will Dunham and Jonathan Oatis)