ɪn nˈaɪntiːnhˈʌndɹɪd nˈaɪnti tˈuː ˌʌndɚ ðə ɡˈʌvɚnmənt ʌv sˈeɪsɑːɹ ɡævˈɪɹiə sˈɜːpə lˈɛd ðə fˈeɪld nᵻɡˌoʊʃɪˈeɪʃən ɐtˈɛmpts wɪððɪ ˌiːˌɛlˈɛn ɡɛɹˈɪləz ɪn tˈiːlækskˈɑːlə, mˈɛksɪkˌoʊ.
In 1992 under the government of César Gaviria Serpa led the failed negotiation attempts with the ELN guerrillas in Tlaxcala, Mexico.