BOGOTA, Colombia (CNN) --Colombian government officials said Sunday they
suspect members of a rebel group are responsible for the execution-style killings of
three people, including a senator, whose bodies were found over the weekend.

The bodies of Sen. Martha Catalina Daniels, her chauffeur and bodyguard, Carlos
Lozano, and her friend, Ana Maria Medina, whose husband is being held by the rebel
group, were found off a country road near Zipacon, Daniels' home district 25 miles
west of the capital, police said.

Each had been shot twice in the head, and their bodies showed signs of torture, said
police Cmdr. Alvaro Sandoval. The bodies were taken to Bogota for a forensic
investigation.

Authorities say Daniels, a member of the Liberal opposition party, was serving as an
intermediary to negotiate the release of hostages. The three had been missing since
early Saturday, when they left together in Daniels' Mercedes Benz truck for an
undisclosed destination, unaccompanied by a security contingent. Daniels had called
for a security escort at 8 a.m. local time Saturday, but the group set out three hours
earlier.

Colombia's attorney general, Louis Camillo Osorio, told reporters that all indications
pointed to an assassination by the Armed Revolutionary Forces of Colombia rebel
group, also known as FARC.

There was no immediate claim of responsibility for the killings.

FARC, Colombia's largest rebel group, has been locked in confrontation with the
Colombian military since February 21, when President Andres Pastrana broke off
peace talks and ordered the military to re-take a safe haven the rebel group had been
operating in for three years, in the southern part of the country.

Pastrana's orders came after FARC rebels hijacked a commercial airliner carrying
Sen. Jorge Eduardo Gechen, chairman of the Colombian Senate's peace commission.
He and five senators are being held captive by FARC, which has demanded the
release of some 200 rebels being held by the Colombian government.

The killings also come a week before national congressional elections and less than
three months before the presidential election.

On February 23, presidential candidate Ingrid Betancourt was kidnapped by FARC,
which offered to exchange her and others it holds captive for the release of
government-held prisoners. The government rejected the offer.

-- CNN en Español Correspondent Fernando Ramos contributed to this report.